Nanostructure ink compositions for inkjet printing

ABSTRACT

The invention pertains to the field of nanotechnology. The disclosure provides nanostructure compositions comprising (a) at least one organic solvent; (b) at least one population of nanostructures comprising a core and at least one shell, wherein the nanostructures comprise inorganic ligands bound to the surface of the nanostructures; and (c) at least one poly(alkylene oxide) additive. The nanostructure compositions comprising at least one poly(alkylene oxide) additive show improved solubility in organic solvents. And, the nanostructure compositions show increased suitability for use in inkjet printing. The disclosure also provides methods of producing emissive layers using the nanostructure compositions.

BACKGROUND OF THE INVENTION Field of the Invention

The invention pertains to the field of nanotechnology. The disclosureprovides nanostructure compositions comprising (a) at least one organicsolvent; (b) at least one population of nanostructures comprising a coreand at least one shell, wherein the nanostructures comprise inorganicligands bound to the surface of the nanostructures; and (c) at least onepoly(alkylene oxide) additive. The nanostructure compositions comprisingat least one poly(alkylene oxide) additive show improved solubility inorganic solvents. And, the nanostructure compositions show increasedsuitability for use in inkjet printing. The disclosure also providesmethods of producing emissive layers using the nanostructurecompositions.

Background Art

Semiconductor nanostructures can be incorporated into a variety ofelectronic and optical devices. The electrical and optical properties ofsuch nanostructures vary, e.g., depending on their composition, shape,and size. For example, size-tunable properties of semiconductornanostructures are of great interest for applications such aselectroluminescent devices, lasers, and biomedical labeling. Highlyluminescent nanostructures are particularly desirable forelectroluminescent device applications.

Methods for the inkjet printing of nanostructures to make electronicdevices are known. See, for example, U.S. Patent Appl. Publication Nos.2019/0062581, 2019/0039294, 2018/0230321, and 2002/0156156 and U.S. Pat.No. 8,765,014.

U.S. Patent Appl. Publication No. 2018/0230321 discloses inks ofCdZnS/ZnS quantum dots (blue), CdZnSeS/ZnS quantum dots (green), andCdSe/CdS/ZnS quantum dots (red) containing oleate and trioctylphosphineligands. The inks were obtained by adding the quantum dots to asubstituted aromatic or heteroaromatic solvent such as1-methoxynaphthalene, cyclohexylbenzene, 3-isopropylbiphenyl, benzylbenzoate, 1-tetralone, or 3-phenoxytoluene at a concentration of 5weight % and mixing and heating until the quantum dots were fullydispersed.

WO2017/079255 discloses semiconductor nanocrystals with halometallateligands, wherein the halometallate ligand has the formula MX₃ ⁻, MX₄ ⁻or MX₄ ²⁻, and wherein M is a metal from Group 12 or Group 13 of theperiodic table and X is halide. Particular halometallate ligands includeCdCl₃ ⁻, CdCl₄ ²⁻, CdBr₃ ⁻, CdBr₄ ²⁻, HgCl₃ ⁻, ZnCl₃ ⁻, ZnCl₄ ²⁻, andZnBr₄ ²⁻. The semiconductor nanocrystals with halometallate ligands weremade by forming a solution of the corresponding organic ligand-cappedsemiconductor nanocrystals and the halometallate anions and maintainingthe solution under conditions that allowed the halometallate anions toundergo ligand exchange with the organic ligands.

BRIEF SUMMARY OF THE INVENTION

The present disclosure provides a nanostructure composition comprising:

-   -   (a) at least one organic solvent;    -   (b) at least one nanostructure comprising a core and at least        one shell, wherein the nanostructure comprises inorganic ligands        bound to the surface of the nanostructure; and    -   (c) at least one poly(alkylene oxide) additive.

In some embodiments, the core in the nanostructure composition comprisesat least one of Si, Ge, Sn, Se, Te, B, C, P, BN, BP, BAs, AlN, AlP,AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, ZnO, ZnS, ZnSe,ZnTe, CdS, CdSe, CdSeZn, CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS,MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl,CuBr, CuI, Si₃N₄, Ge₃N₄, Al₂O₃, Al₂OC, or combinations thereof.

In some embodiments, the core in the nanostructure composition comprisesInP.

In some embodiments, the at least one shell in the nanostructurecomposition comprises CdS, CdSe, CdO, CdTe, ZnS, ZnO, ZnSe, ZnTe, MgTe,GaAs, GaSb, GaN, HgO, HgS, HgSe, HgTe, InAs, InSb, InN, AlAs, AlN, AlSb,AlS, PbS, PbO, PbSe, PbTe, MgO, MgS, MgSe, MgTe, CuCl, Ge, Si, or alloysthereof.

In some embodiments, the at least one shell in the nanostructurecomposition comprises a first shell comprising ZnSe and a second shellcomprising ZnS.

In some embodiments, the inorganic ligand in the nanostructurecomposition comprises a halometallate anion.

In some embodiments, the halometallate anion in the nanostructurecomposition is fluorozincate, tetrafluoroborate, or hexafluorophosphate.

In some embodiments, the halometallate anion in the nanostructurecomposition has the structure of one of Formulas (I)-(III):MX₃ ⁻  (I);MX_(4-x)Y_(x) ⁻  (II);or MX_(4-x)Y_(x) ²⁻  (III);wherein:

-   -   M is selected from the group consisting of Zn, Cd, Hg, Cu, Ag,        and Au;    -   X is selected from the group consisting of Br, Cl, F, and I;    -   Y is selected from the group consisting of Br, Cl, F, and I; and    -   x is 0, 1, or 2.

In some embodiments, the halometallate anion in the nanostructurecomposition is CdCl₃ ⁻, CdCl₄ ²⁻, CdI₃ ⁻, CdBr₃ ⁻, CdBr₄ ²⁻, InCl₄ ⁻,HgCl₃ ⁻, ZnCl₃ ⁻, ZnCl₄ ²⁻, or ZnBr₄ ²⁻.

In some embodiments, the inorganic ligand in the nanostructurecomposition comprises an organic cation is selected from the groupconsisting of a tetraalkylammonium cation, an alkylphosphonium cation, aformamidinium cation, a guanidinium cation, an imidazolium cation, and apyridinium cation.

In some embodiments, the inorganic ligand in the nanostructurecomposition comprises a tetraalkylammonium cation.

In some embodiments, the inorganic ligand in the nanostructurecomposition comprises a tetraalkylammonium cation selected from thegroup consisting of dioctadecyldimethylammonium,dihexadecyldimethylammonium, ditetradecyldimethylammonium,didodecyldimethylammonium, didecyldimethylammonium,dioctyldimethylammonium, bis(ethylhexyl)dimethylammonium,octadecyltrimethylammonium, oleyltrimethylammonium,hexadecyltrimethylammonium, tetradecyltrimethylammonium,dodecyltrimethylammonium, decyltrimethylammonium,octyltrimethylammonium, phenylethyltrimethylammonium,benzyltrimethylammonium, phenyltrimethylammonium,benzylhexadecyldimethylammonium, benzyltetradecyldimethylammonium,benzyldodecyldimethylammonium, benzyldecyldimethylammonium,benzyloctyldimethylammonium, benzyltributylammonium,benzyltriethylammonium, tetrabutylammonium, tetrapropylammonium,diisopropyldimethylammonium, tetraethylammonium, andtetramethylammonium.

In some embodiments, the organic ligand in the nanostructure compositioncomprises a ZnF₄ ⁻ anion and a didecyldimethylammonium cation.

In some embodiments, the organic ligand in the nanostructure compositioncomprises an alkylphosphonium cation.

In some embodiments, the alkyphosphonium cation in the nanostructurecomposition is selected from the group consisting oftetraphenylphosphonium, dimethyldiphenylphosphonium,methyltriphenoxyphosphonium, hexadecyltributylphosphonium,octyltributylphosphonium, tetradecyltrihexylphosphonium,tetrakis(hydroxymethyl)phosphonium, tetraoctylphosphonium,tetrabutylphosphonium, and tetramethylphosphonium.

In some embodiments, the weight percentage of nanostructures in thenanostructure composition is between about 0.5% and about 10%.

In some embodiments, the organic solvent in the nanostructurecomposition has a boiling point at 1 atmosphere of about 250° C. toabout 350° C.

In some embodiments, the organic solvent in the nanostructurecomposition has a viscosity of about 1 mPa·s to about 15 mPa s.

In some embodiments, the organic solvent in the nanostructurecomposition has a surface tension of about 20 dyne/cm to about 50dyne/cm.

In some embodiments, the organic solvent in the nanostructurecomposition is an alkylnaphthalene, an alkoxynaphthalene, analkylbenzene, an aryl, an alkyl-substituted benzene, acycloalkylbenzene, a C₉-C₂₀ alkane, a diarylether, an alkyl benzoate, anaryl benzoate, or an alkoxy-substituted benzene.

In some embodiments, the organic solvent in the nanostructurecomposition is selected from the group consisting of 1-tetralone,3-phenoxytoluene, acetophenone, 1-methoxynaphthalene, n-octylbenzene,n-nonylbenzene, 4-methylanisole, n-decylbenzene, p-diisopropylbenzene,pentylbenzene, tetralin, cyclohexylbenzene, chloronaphthalene,1,4-dimethylnaphthalene, 3-isopropylbiphenyl, p-methylcumene,dipentylbenzene, o-diethylbenzene, m-diethylbenzene, p-diethylbenzene,1,2,3,4-tetramethylbenzene, 1,2,3,5-tetramethylbenzene,1,2,4,5-tetrametylbenzene, butylbenzene, dodecylbenzene,1-methylnaphthalene, 1,2,4-trichlorobenzene, diphenyl ether,diphenylmethane, 4-isopropylbiphenyl, benzyl benzoate,1,2-bi(3,4-dimethylphenyl)ethane, 2-isopropylnaphthalene, dibenzylether, and combinations thereof.

In some embodiments, the organic solvent in the nanostructurecomposition is 1-methylnaphthalene, n-octylbenzene,1-methoxynapththalene, 3-phenoxytoluene, cyclohexylbenzene,4-methylanisole, n-decylbenzene, or a combination thereof.

In some embodiments, the weight percentage of the organic solvent in thenanostructure composition is between about 70% and about 99%.

In some embodiments, the at least one poly(alkylene oxide) in thenanostructure composition has Formula (IV):

wherein:

-   -   x is 1 to 100;    -   y is 0 to 100;    -   R^(1A) and R^(1B) independently are H or C₁₋₂₀ alkyl;    -   R² is C₁₋₂₀ alkyl;    -   X₁ is a bond or C₁₋₁₂ alkyl;    -   X₂ is a bond, —O—, —OC(═O)—, or amido;    -   FG is —OH, —NH₂, —NH₄ ⁺, —N₃, —C(═O)OR³, —P(═O)(OR⁴)₃, or        —P(R⁵)₄;    -   R³ is H, C₁₋₂₀ alkyl, or C₆₋₁₄ aryl;    -   R⁴ is independently H, C₁₋₂₀ alkyl, or C₆₋₁₄ aryl; and    -   R⁵ is independently H, C₁₋₂₀ alkyl, or C₆₋₁₄ aryl.

In some embodiments, x is 2-20 and y is 1-10 in the at least onepoly(alkylene oxide) having Formula (IV) in the nanostructurecomposition.

In some embodiments, R^(1A) is H and R^(1B) is CH₃ in the at least onepoly(alkylene oxide) having Formula (IV) in the nanostructurecomposition.

In some embodiments, X₁ is a bond and X₂ is a bond in the at least onepoly(alkylene oxide) having Formula (IV) in the nanostructurecomposition.

In some embodiments, FG is —OH, —NH₂, —N₃, or —CO₂H in the at least onepoly(alkylene oxide) having Formula (IV) in the nanostructurecomposition.

In some embodiments, the at least one poly(alkylene oxide) in thenanostructure composition has Formula VI:

wherein:

-   -   x is 1 to 100;    -   y is 0 to 100; and    -   R² is C₁₋₂₀ alkyl.

In some embodiments, x is 19, y is 3, and R₂ is —CH₃ in the at least onepoly(alkylene oxide) having Formula (VI) in the nanostructurecomposition.

In some embodiments, the weight percentage of the poly(alkylene oxide)additive in the nanostructure composition is between about 0.05% andabout 2%.

In some embodiments, the nanostructure composition further comprises asurface-active compound, a lubricating agent, a wetting agent, adispersing agent, a hydrophobing agent, an adhesive agent, a flowimprover, a defoaming agent, a deaerator, a diluent, a stabilizer, anantioxidant, a viscosity modifier, an inhibitor, or a combinationthereof.

The present disclosure also provides a process comprising depositing thenanostructure composition described herein to form a layer on asubstrate.

In some embodiments, the nanostructure composition is deposited byinkjet printing.

In some embodiments, the process of depositing the nanostructurecomposition comprises at least partial removal of the organic solvent.

In some embodiments, the process of depositing the nanostructurecomposition comprises at least partial removal of the organic solvent byvacuum drying.

In some embodiments, the process of depositing the nanostructurecomposition comprises at least partial removal of the organic solvent byapplication of heat.

In some embodiments, the substrate is a first conductive layer.

In some embodiments, the process of depositing the nanostructurecomposition further comprises depositing a second conductive layer onthe nanostructure composition.

In some embodiments, the process of depositing the nanostructurecomposition further comprises depositing a first transport layer on thefirst conductive layer, the first transport layer being configured tofacilitate the transport of holes from the first conductive layer to thelayer comprising the nanostructure composition; and depositing a secondtransport layer on the layer comprising the nanostructure composition,the second transport layer configured to facilitate the transport ofelectrons from the second conductive layer to the layer comprising thenanostructure composition.

In some embodiments, the nanostructure composition is deposited in apattern.

The present disclosure also provides a light emitting diode comprising:

-   -   (a) a first conductive layer;    -   (b) a second conductive layer; and    -   (c) an emitting layer between the first conductive layer and the        second conductive layer, wherein the emitting layer comprises at        least one population of nanostructures, wherein the        nanostructures comprise (i) at least one organic solvent; (ii)        at least one nanostructure comprising a core and at least one        shell, wherein the nanostructure comprises inorganic ligands        bound to the surface of the nanostructure; and (iii) at least        one poly(alkylene oxide) additive.

BRIEF DESCRIPTION OF THE DRAWING

The FIG. 1 is a flow chart showing the ligand exchange procedure ofExample 2. In the first step, t-butylammonium fluoride (TBAF) and zincdifluoride (ZnF₂) were admixed in N-methylformamide (NMF) at roomtemperature to produce the dianionic halozincate TBA₂ZnF₄. In the secondstep, the dianionic halozincate TBA₂ZnF₄ and oleate-capped quantum dots(QD-OA) were admixed in a mixture of toluene and NMF at 70° C. toproduce TBA-ZnF₄-capped quantum dots. In the third step, theTBA-ZnF₄-capped quantum dots were washed with toluene. In a fourth step,TBA-ZnF₄-capped quantum dots were admixed with didecyldimethylammoniumchloride (DDA-Cl) to produce DDA-ZnF₄-capped quantum dots. In a fifthstep, the DDA-ZnF₄-capped quantum dots were precipitated withacetonitrile. In a sixth step, the DDA-ZnF₄-capped quantum dots wereredispersed in toluene in preparation for use in a device.

DETAILED DESCRIPTION OF THE INVENTION Definitions

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which the invention pertains. The following definitionssupplement those in the art and are directed to the current applicationand are not to be imputed to any related or unrelated case, e.g., to anycommonly owned patent or application. Although any methods and materialssimilar or equivalent to those described herein can be used in thepractice for testing of the present invention, the preferred materialsand methods are described herein. Accordingly, the terminology usedherein is for the purpose of describing particular embodiments only, andis not intended to be limiting.

As used in this specification and the appended claims, the singularforms “a,” “an,” and “the” include plural referents unless the contextclearly dictates otherwise. Thus, for example, reference to “ananostructure” includes a plurality of such nanostructures, and thelike.

The term “about” as used herein indicates the value of a given quantityvaries by +/−10% of the value. For example, “about 100 nm” encompasses arange of sizes from 90 nm to 110 nm, inclusive.

A “nanostructure” is a structure having at least one region orcharacteristic dimension with a dimension of less than about 500 nm. Insome embodiments, the nanostructure has a dimension of less than about200 nm, less than about 100 nm, less than about 50 nm, less than about20 nm, or less than about 10 nm. Typically, the region or characteristicdimension will be along the smallest axis of the structure. Examples ofsuch structures include nanowires, nanorods, nanotubes, branchednanostructures, nanotetrapods, tripods, bipods, nanocrystals, nanodots,quantum dots, nanoparticles, and the like. Nanostructures can be, e.g.,substantially crystalline, substantially monocrystalline,polycrystalline, amorphous, or a combination thereof. In someembodiments, each of the three dimensions of the nanostructure has adimension of less than about 500 nm, less than about 200 nm, less thanabout 100 nm, less than about 50 nm, less than about 20 nm, or less thanabout 10 nm.

The term “heterostructure” when used with reference to nanostructuresrefers to nanostructures characterized by at least two different and/ordistinguishable material types. Typically, one region of thenanostructure comprises a first material type, while a second region ofthe nanostructure comprises a second material type. In certainembodiments, the nanostructure comprises a core of a first material andat least one shell of a second (or third etc.) material, where thedifferent material types are distributed radially about the long axis ofa nanowire, a long axis of an arm of a branched nanowire, or the centerof a nanocrystal, for example. A shell can but need not completely coverthe adjacent materials to be considered a shell or for the nanostructureto be considered a heterostructure; for example, a nanocrystalcharacterized by a core of one material covered with small islands of asecond material is a heterostructure. In other embodiments, thedifferent material types are distributed at different locations withinthe nanostructure; e.g., along the major (long) axis of a nanowire oralong a long axis of arm of a branched nanowire. Different regionswithin a heterostructure can comprise entirely different materials, orthe different regions can comprise a base material (e.g., silicon)having different dopants or different concentrations of the same dopant.

As used herein, the “diameter” of a nanostructure refers to the diameterof a cross-section normal to a first axis of the nanostructure, wherethe first axis has the greatest difference in length with respect to thesecond and third axes (the second and third axes are the two axes whoselengths most nearly equal each other). The first axis is not necessarilythe longest axis of the nanostructure; e.g., for a disk-shapednanostructure, the cross-section would be a substantially circularcross-section normal to the short longitudinal axis of the disk. Wherethe cross-section is not circular, the diameter is the average of themajor and minor axes of that cross-section. For an elongated or highaspect ratio nanostructure, such as a nanowire, the diameter is measuredacross a cross-section perpendicular to the longest axis of thenanowire. For a spherical nanostructure, the diameter is measured fromone side to the other through the center of the sphere.

The terms “crystalline” or “substantially crystalline,” when used withrespect to nanostructures, refer to the fact that the nanostructurestypically exhibit long-range ordering across one or more dimensions ofthe structure. It will be understood by one of skill in the art that theterm “long range ordering” will depend on the absolute size of thespecific nanostructures, as ordering for a single crystal cannot extendbeyond the boundaries of the crystal. In this case, “long-rangeordering” will mean substantial order across at least the majority ofthe dimension of the nanostructure. In some instances, a nanostructurecan bear an oxide or other coating, or can be comprised of a core and atleast one shell. In such instances it will be appreciated that theoxide, shell(s), or other coating can but need not exhibit such ordering(e.g. it can be amorphous, polycrystalline, or otherwise). In suchinstances, the phrase “crystalline,” “substantially crystalline,”“substantially monocrystalline,” or “monocrystalline” refers to thecentral core of the nanostructure (excluding the coating layers orshells). The terms “crystalline” or “substantially crystalline” as usedherein are intended to also encompass structures comprising variousdefects, stacking faults, atomic substitutions, and the like, as long asthe structure exhibits substantial long range ordering (e.g., order overat least about 80% of the length of at least one axis of thenanostructure or its core). In addition, it will be appreciated that theinterface between a core and the outside of a nanostructure or between acore and an adjacent shell or between a shell and a second adjacentshell may contain non-crystalline regions and may even be amorphous.This does not prevent the nanostructure from being crystalline orsubstantially crystalline as defined herein.

The term “monocrystalline” when used with respect to a nanostructureindicates that the nanostructure is substantially crystalline andcomprises substantially a single crystal. When used with respect to ananostructure heterostructure comprising a core and one or more shells,“monocrystalline” indicates that the core is substantially crystallineand comprises substantially a single crystal.

A “nanocrystal” is a nanostructure that is substantiallymonocrystalline. A nanocrystal thus has at least one region orcharacteristic dimension with a dimension of less than about 500 nm. Insome embodiments, the nanocrystal has a dimension of less than about 200nm, less than about 100 nm, less than about 50 nm, less than about 20nm, or less than about 10 nm. The term “nanocrystal” is intended toencompass substantially monocrystalline nanostructures comprisingvarious defects, stacking faults, atomic substitutions, and the like, aswell as substantially monocrystalline nanostructures without suchdefects, faults, or substitutions. In the case of a nanocrystalheterostructure comprising a core and one or more shells, the core ofthe nanocrystal is typically substantially monocrystalline, but theshell(s) need not be. In some embodiments, each of the three dimensionsof the nanocrystal has a dimension of less than about 500 nm, less thanabout 200 nm, less than about 100 nm, less than about 50 nm, less thanabout 20 nm, or less than about 10 nm.

The term “quantum dot” (or “dot”) refers to a nanocrystal that exhibitsquantum confinement or exciton confinement. Quantum dots can besubstantially homogeneous in material properties, or in certainembodiments, can be heterogeneous, e.g., including a core and at leastone shell. The optical properties of quantum dots can be influenced bytheir particle size, chemical composition, and/or surface composition,and can be determined by suitable optical testing available in the art.The ability to tailor the nanocrystal size, e.g., in the range betweenabout 1 nm and about 15 nm, enables photoemission coverage in the entireoptical spectrum to offer great versatility in color rendering.

As used herein, the term “monolayer” is a measurement unit of shellthickness derived from the bulk crystal structure of the shell materialas the closest distance between relevant lattice planes. By way ofexample, for cubic lattice structures the thickness of one monolayer isdetermined as the distance between adjacent lattice planes in the [111]direction. By way of example, one monolayer of cubic ZnSe corresponds to0.328 nm and one monolayer of cubic ZnS corresponds to 0.31 nmthickness. The thickness of a monolayer of alloyed materials can bedetermined from the alloy composition through Vegard's law.

As used herein, the term “shell” refers to material deposited onto thecore or onto previously deposited shells of the same or differentcomposition and that result from a single act of deposition of the shellmaterial. The exact shell thickness depends on the material as well asthe precursor input and conversion and can be reported in nanometers ormonolayers. As used herein, “target shell thickness” refers to theintended shell thickness used for calculation of the required precursoramount. As used herein, “actual shell thickness” refers to the actuallydeposited amount of shell material after the synthesis and can bemeasured by methods known in the art. By way of example, actual shellthickness can be measured by comparing particle diameters determinedfrom transmission electron microscopy (TEM) images of nanocrystalsbefore and after a shell synthesis.

As used herein, the term “layer” refers to material deposited onto thecore or onto previously deposited layers and that result from a singleact of deposition of the core or shell material. The exact thickness ofa layer is dependent on the material. For example, a ZnSe layer may havea thickness of about 0.328 nm and a ZnS layer may have a thickness ofabout 0.31 nm.

A “ligand” is a molecule capable of interacting (whether weakly orstrongly) with one or more faces of a nanostructure, e.g., throughcovalent, ionic, van der Waals, or other molecular interactions with thesurface of the nanostructure.

“Photoluminescence quantum yield” is the ratio of photons emitted tophotons absorbed, e.g., by a nanostructure or population ofnanostructures. As known in the art, quantum yield is typicallydetermined by a comparative method using well-characterized standardsamples with known quantum yield values.

“Peak emission wavelength” (PWL) is the wavelength where the radiometricemission spectrum of the light source reaches its maximum.

As used herein, the term “full width at half-maximum” (FWHM) is ameasure of the size distribution of quantum dots. The emission spectraof quantum dots generally have the shape of a Gaussian curve. The widthof the Gaussian curve is defined as the FWHM and gives an idea of thesize distribution of the particles. A smaller FWHM corresponds to anarrower quantum dot nanocrystal size distribution. FWHM is alsodependent upon the emission wavelength maximum.

As used herein, the term “external quantum efficiency” (EQE) is a ratioof the number of photons emitted from a light emitting diode to thenumber of electrons passing through the device. The EQE measures howefficiently a light emitting diode converts electrons to photons andallows them to escape. EQE can be measured using the formula:EQE=[injection efficiency]×[solid-state quantum yield]×[extractionefficiency]where:

-   -   injection efficiency=the proportion of electrons passing through        the device that are injected into the active region;    -   solid-state quantum yield=the proportion of all electron-hole        recombinations in the active region that are radiative and thus,        produce photons; and    -   extraction efficiency=the proportion of photons generated in the        active region that escape from the device.

As used herein, the term “stable” refers to a mixture or compositionthat resists change or decomposition due to internal reaction or due tothe action of air, heat, light, pressure, other natural conditions,voltage, current, luminance, or other operation conditions. Thecolloidal stability of a nanostructure composition can be determined bymeasuring the peak absorption wavelength after admixing at least onepopulation of nanostructures with at least one solvent. The peakabsorption wavelength can be measured by irradiating a nanostructurecomposition with UV or blue (450 nm) light and measuring the output witha spectrometer. The absorption spectrum is compared to the absorptionfrom the original nanostructure composition. A colloid nanostructurecomposition is stable if the peak absorption wavelength does not shiftby more than 5 nm.

“Alkyl” as used herein refers to a straight or branched, saturated,aliphatic radical having the number of carbon atoms indicated. In someembodiments, the alkyl is C₁₋₂ alkyl, C₁₋₃ alkyl, C₁₋₄ alkyl, C₁₋₅alkyl, C₁₋₆ alkyl, C₁₋₇ alkyl, C₁₋₈ alkyl, C₁₋₉ alkyl, C₁₋₁₀ alkyl,C₁₋₁₂ alkyl, C₁₋₁₄ alkyl, C₁₋₁₆ alkyl, C₁₋₁₈ alkyl, C₁₋₂₀ alkyl, C₈₋₂₀alkyl, C₁₂₋₂₀ alkyl, C₁₄₋₂₀ alkyl, C₁₆₋₂₀ alkyl, or C₁₈₋₂₀ alkyl. Forexample, C₁₋₆ alkyl includes, but is not limited to, methyl, ethyl,propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl,isopentyl, and hexyl. In some embodiments, the alkyl is octyl, nonyl,decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl,heptadecyl, octadecyl, nonadecyl, or icosanyl.

The term “alkylene,” as used herein, alone or in combination, refers toa saturated aliphatic group derived from a straight or branched chainsaturated hydrocarbon attached at two or more positions, such asmethylene (—CH₂—). Unless otherwise specified, the term “alkyl” mayinclude “alkylene” groups.

“Amido” as used herein, refers to both “aminocarbonyl” and“carbonylamino.” These terms when used alone or in connection withanother group refers to an amido group such as N(R^(L)R^(M))—C(O)— orR^(M)C(O)N(R^(L))— when used terminally and —C(O)—N(R^(L))— or—N(R^(M))—C(O)— when used internally, wherein each of R′ and R^(M) isindependently hydrogen, alkyl, cycloaliphatic,(cycloaliphatic)aliphatic, aryl, araliphatic, heterocycloaliphatic,(heterocycloaliphatic)aliphatic, heteroaryl, carboxy, sulfanyl,sulfinyl, sulfonyl, (aliphatic)carbonyl, (cycloaliphatic)carbonyl,((cycloaliphatic)aliphatic)carbonyl, arylcarbonyl,(araliphatic)carbonyl, (heterocycloaliphatic)carbonyl,((heterocycloaliphatic)aliphatic)carbonyl, (heteroaryl)carbonyl, or(heteroaraliphatic)carbonyl, each of which being defined herein andbeing optionally substituted. Examples of amino groups includealkylamino, dialkylamino, or arylamino. Examples of amido groups includealkylamido (such as alkylcarbonylamino or alkylcarbonylamino),(heterocycloaliphatic)amido, (heteroaralkyl)amido, (heteroaryl)amido,(heterocycloalkyl)alkylamido, arylamido, aralkylamido,(cycloalkyl)alkylamido, or cycloalkylamido.

“Aryl” or “aromatic” as used herein refers to unsubstituted monocyclicor bicyclic aromatic ring systems having from six to fourteen carbonatoms, i.e., a C₆₋₁₄ aryl. Non-limiting exemplary aryl groups includephenyl, naphthyl, phenanthryl, anthracyl, indenyl, azulenyl, biphenyl,biphenylenyl, fluorenyl groups, terphenyl, pyrenyl,9,9-dimethyl-2-fluorenyl, anthryl, triphenylenyl, chrysenyl,fluorenylidenephenyl, and 5H-dibenzo[a,d]cycloheptenylidenephenyl. Inone embodiment, the aryl group is a phenyl, naphthyl, or9,9-dimethyl-2-fluorenyl.

The terms “halogen” and “halide” as used herein refers to a fluorine,chlorine, bromine or iodine atom.

Unless clearly indicated otherwise, ranges listed herein are inclusive.

A variety of additional terms are defined or otherwise characterizedherein.

Inkjet Printing

The formation of thin films using dispersions of nanostructures inorganic solvents is often achieved by coating techniques such as spincoating. However, these coating techniques are generally not suitablefor the formation of thin films over a large area and do not provide ameans to pattern the deposited layer and thus, are of limited use.Inkjet printing allows for precisely patterned placement of thin filmson a large scale at low cost. Inkjet printing also allows for precisepatterning of nanostructure layers, allows printing pixels of a display,and eliminates the need for photo-patterning. Thus, inkjet printing isvery attractive for industrial application—particularly in displayapplications.

Inkjet printing is a promising technology for generating patternedstructures of functional materials such as the pixel array in quantumdot electroluminescent (QDEL) and quantum dot color conversion (QDCC)displays. Inkjet printing is more cost-effective than other printingtechnology, such as photolithography, due to its requiring fewer processsteps and its almost complete utilization of material. Quantum dots areoften marketed as printable because they are soluble in organicsolvents. However, suitable inks for inkjet printing are required tomeet several requirements and the actual printing of a quantum dot inkis not a trivial process.

Inkjet printing of a QDEL display requires the following:

-   -   (1) printer head compatibility with respect to swelling and        corrosion;    -   (2) a high boiling point solvent (>240° C.) to prevent ink        drying and nozzle clogging;    -   (3) suitable viscosity (1-12 mPa.$) and surface tension (28-44        dyne/cm) of the ink to provide jettability (e.g., drop formation        and nozzle wetting); and    -   (4) high quantum dot solubility and preservation of emissive        properties.

Thus, the compatibility of quantum dots to more polar solventscomprising ester or ether groups needs to be improved, which would thenenable the formulation of an ink with suitable viscosity and surfacetension.

Nanostructure Composition

In some embodiments, the present disclosure provides a nanostructurecomposition comprising:

-   -   (a) at least one organic solvent;    -   (b) at least one nanostructure comprising a core and at least        one shell, wherein the nanostructure comprises inorganic ligands        bound to the surface of the nanostructure; and    -   (c) at least one poly(alkylene oxide) additive.

In some embodiments, the present disclosure provides a nanostructurecomposition comprising:

-   -   (a) at least one organic solvent;    -   (b) at least one nanostructure comprising a core and at least        one shell, wherein the nanostructure comprises inorganic ligands        bound to the surface of the nanostructure, wherein the inorganic        ligands comprise a halometallate anion and an organic cation;        and    -   (c) at least one poly(alkylene oxide) additive.

In some embodiments, the nanostructure composition is a nanostructureink composition.

Nanostructures

In some embodiments, the nanostructure comprises a core and at least oneshell. In some embodiments, the nanostructure comprises a core and 1, 2,3, 4, 5, 6, 7, 8, 9, or shells. In some embodiments, the nanostructurecomprises a core and one shell. In some embodiments, the nanostructurecomprises a core and two shells. In some embodiments, the nanostructurecomprises a core and three shells. In some embodiments, thenanostructure comprises at least two shells wherein the two shells aredifferent.

In some embodiments, the nanostructure comprises organic (first)ligands. In some embodiments, the nanostructure comprises inorganic(second) ligands. In some embodiments, the nanostructure comprises amixture of organic (first) ligands and inorganic (second) ligands.

In some embodiments, the nanostructure comprises an InP core and a ZnSeshell. In some embodiments, the nanostructure is InP/ZnS. In someembodiments, the nanostructure is a red-emitting InP/ZnS. In someembodiments, the nanostructure is a green-emitting InP/ZnS.

In some embodiments, the nanostructure comprises an InP core, a ZnSeshell, and a ZnS shell. In some embodiments, the nanostructure isInP/ZnSe/ZnS. In some embodiments, the nanostructure is a red-emittingInP/ZnSe/ZnS. In some embodiments, the nanostructure is a green-emittingInP/ZnSe/ZnS.

In some embodiments, the nanostructure comprises a ZnSe core and a ZnSshell. In some embodiments, the nanostructure is ZnSe/ZnS. In someembodiments, the nanostructure is a blue-emitting ZnSe/ZnS.

In some embodiments, the nanostructure comprises a ZnSeTe core, a ZnSeshell, and a ZnS shell. In some embodiments, the nanostructure isZnSeTe/ZnSe/ZnS. In some embodiments, the nanostructure is ablue-emitting ZnSeTe/ZnSe/ZnS.

The number of monolayers will determine the size of the core/shell(s)nanostructures. The size of the core/shell(s) nanostructures can bedetermined using techniques known to those of skill in the art. In someembodiments, the size of the core/shell(s) nanostructures is determinedusing TEM. In some embodiments, the core/shell(s) nanostructures have anaverage diameter of between about 1 nm and about 15 nm, about 1 nm andabout 10 nm, about 1 nm and about 9 nm, about 1 nm and about 8 nm, about1 nm and about 7 nm, about 1 nm and about 6 nm, about 1 nm and about 5nm, about 5 nm and about 15 nm, about 5 nm and about 10 nm, about 5 nmand about 9 nm, about 5 nm and about 8 nm, about 5 nm and about 7 nm,about 5 nm and about 6 nm, about 6 nm and about 15 nm, about 6 nm andabout 10 nm, about 6 nm and about 9 nm, about 6 nm and about 8 nm, about6 nm and about 7 nm, about 7 nm and about 15 nm, about 7 nm and about 10nm, about 7 nm and about 9 nm, about 7 nm and about 8 nm, about 8 nm andabout 15 nm, about 8 nm and about 10 nm, about 8 nm and about 9 nm,about 9 nm and about 15 nm, about 9 nm and about 10 nm, or about 10 nmand about 15 nm. In some embodiments, the core/shell(s) nanostructureshave an average diameter of between about 6 nm and about 7 nm.

In some embodiments, the weight percentage of nanostructures in thenanostructure composition is between about 0.5% and about 10%. In someembodiments, the weight percentage of nanostructures in thenanostructure composition is between about 0.5% and about 10%, about0.5% and about 5%, about 0.5% and about 3%, about 0.5% and about 2%,about 0.5% and about 1.5%, about 0.5% and about 1%, about 1% and about10%, about 1% and about 5%, about 1% and about 3%, about 1% and about2%, about 1% and about 1.5%, about 1.5% and about 10%, about 1.5% andabout 5%, about 1.5% and about 3%, about 1.5% and about 2%, about 2% andabout 10%, about 2% and about 5%, about 2% and about 3%, about 3% andabout 10%, about 3% and about 5%, or about 5% and about 10%. In someembodiments, the weight percentage of nanostructures in thenanostructure composition is between about 1.5% and about 3%.

Nanostructure Cores

In some embodiments, the core comprises Si, Ge, Sn, Se, Te, B, C, P, BN,BP, BAs, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs,InSb, ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdSeZn, CdTe, HgS, HgSe, HgTe,BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS,PbSe, PbTe, CuF, CuCl, CuBr, CuI, Si₃N₄, Ge₃N₄, Al₂O₃, Al₂OC, orcombinations thereof.

In some embodiments, the core is a Group III-V nanostructure. In someembodiments, the core is a Group III-V nanocrystal selected from thegroup consisting of BN, BP, BAs, BSb, AlN, AlP, AlAs, AlSb, GaN, GaP,GaAs, GaSb, InN, InP, InAs, and InSb. In some embodiments, the core isan InP nanocrystal.

The synthesis of Group III-V nanostructures has been described in U.S.Pat. Nos. 5,505,928, 6,306,736, 6,576,291, 6,788,453, 6,821,337,7,138,098, 7,557,028, 8,062,967, 7,645,397, and 8,282,412 and in U.S.Patent Appl. Publication No. 2015/236195. Synthesis of Group III-Vnanostructures has also been described in Wells, R. L., et al., “The useof tris(trimethylsilyl)arsine to prepare gallium arsenide and indiumarsenide,” Chem. Mater. 1:4-6 (1989) and in Guzelian, A. A., et al.,“Colloidal chemical synthesis and characterization of InAs nanocrystalquantum dots,” Appl. Phys. Lett. 69: 1432-1434 (1996).

Synthesis of InP-based nanostructures has been described, e.g., in Xie,R., et al., “Colloidal InP nanocrystals as efficient emitters coveringblue to near-infrared,” J. Am. Chem. Soc. 129:15432-15433 (2007); Micic,O. I., et al., “Core-shell quantum dots of lattice-matched ZnCdSe2shells on InP cores: Experiment and theory,” J. Phys. Chem. B104:12149-12156 (2000); Liu, Z., et al., “Coreduction colloidalsynthesis of III-V nanocrystals: The case of InP,” Angew. Chem. Int. Ed.Engl. 47:3540-3542 (2008); Li, L. et al., “Economic synthesis of highquality InP nanocrystals using calcium phosphide as the phosphorusprecursor,” Chem. Mater. 20:2621-2623 (2008); D. Battaglia and X. Peng,“Formation of high quality InP and InAs nanocrystals in anoncoordinating solvent,” Nano Letters 2:1027-1030 (2002); Kim, S., etal., “Highly luminescent InP/GaP/ZnS nanocrystals and their applicationto white light-emitting diodes,” J. Am. Chem. Soc. 134:3804-3809 (2012);Nann, T., et al., “Water splitting by visible light: A nanophotocathodefor hydrogen production,” Angew. Chem. Int. Ed. 49:1574-1577 (2010);Borchert, H., et al., “Investigation of ZnS passivated InP nanocrystalsby XPS,” Nano Letters 2:151-154 (2002); L. Li and P. Reiss, “One-potsynthesis of highly luminescent InP/ZnS nanocrystals without precursorinjection,” J. Am. Chem. Soc. 130:11588-11589 (2008); Hussain, S., etal. “One-pot fabrication of high-quality InP/ZnS (core/shell) quantumdots and their application to cellular imaging,” Chemphyschem.10:1466-1470 (2009); Xu, S., et al., “Rapid synthesis of high-qualityInP nanocrystals,” J. Am. Chem. Soc. 128:1054-1055 (2006); Micic, O. I.,et al., “Size-dependent spectroscopy of InP quantum dots,” J. Phys.Chem. B 101:4904-4912 (1997); Haubold, S., et al., “Strongly luminescentInP/ZnS core-shell nanoparticles,” Chemphyschem. 5:331-334 (2001);CrosGagneux, A., et al., “Surface chemistry of InP quantum dots: Acomprehensive study,” J. Am. Chem. Soc. 132:18147-18157 (2010); Micic,O. I., et al., “Synthesis and characterization of InP, GaP, and GaInP2quantum dots,” J. Phys. Chem. 99:7754-7759 (1995); Guzelian, A. A., etal., “Synthesis of size-selected, surface-passivated InP nanocrystals,”J. Phys. Chem. 100:7212-7219 (1996); Lucey, D. W., et al.,“Monodispersed InP quantum dots prepared by colloidal chemistry in anon-coordinating solvent,” Chem. Mater. 17:3754-3762 (2005); Lim, J., etal., “InP@ZnSeS, core@composition gradient shell quantum dots withenhanced stability,” Chem. Mater. 23:4459-4463 (2011); and Zan, F., etal., “Experimental studies on blinking behavior of single InP/ZnSquantum dots: Effects of synthetic conditions and UV irradiation,” J.Phys. Chem. C 116:394-3950 (2012). However, such efforts have had onlylimited success in producing InP nanostructures with high quantumyields.

In some embodiments, the core is doped. In some embodiments, the dopantof the nanocrystal core comprises a metal, including one or moretransition metals. In some embodiments, the dopant is a transition metalselected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W,Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, andcombinations thereof. In some embodiments, the dopant comprises anon-metal. In some embodiments, the dopant is ZnS, ZnSe, ZnTe, CdSe,CdS, CdTe, HgS, HgSe, HgTe, CuInS₂, CuInSe₂, AlN, AlP, AlAs, GaN, GaP,or GaAs.

In some embodiments, the core is a Group II-VI nanocrystal selected fromthe group consisting of ZnO, ZnSe, ZnS, ZnTe, CdO, CdSe, CdS, CdTe, HgO,HgSe, HgS, and HgTe. In some embodiments, the core is a nanocrystalselected from the group consisting of ZnSe, ZnS, CdSe, and CdS. Thesynthesis of Group II-VI nanostructures has been described in U.S. Pat.Nos. 6,225,198, 6,322,901, 6,207,229, 6,607,829, 7,060,243, 7,374,824,6,861,155, 7,125,605, 7,566,476, 8,158,193, and 8,101,234 and in U.S.Patent Appl. Publication Nos. 2011/0262752 and 2011/0263062.

In some embodiments, the core is purified before deposition of a shell.In some embodiments, the core is filtered to remove precipitate from thecore solution.

In some embodiments, the core is subjected to an acid etching stepbefore deposition of a shell.

In some embodiments, the diameter of the core is determined usingquantum confinement. Quantum confinement in zero-dimensionalnanocrystallites, such as quantum dots, arises from the spatialconfinement of electrons within the crystallite boundary. Quantumconfinement can be observed once the diameter of the material is of thesame magnitude as the de Broglie wavelength of the wave function. Theelectronic and optical properties of nanoparticles deviate substantiallyfrom those of bulk materials. A particle behaves as if it were free whenthe confining dimension is large compared to the wavelength of theparticle. During this state, the band gap remains at its original energydue to a continuous energy state. However, as the confining dimensiondecreases and reaches a certain limit, typically in nanoscale, theenergy spectrum becomes discrete. As a result, the band gap becomessize-dependent. Size can be determined as is known in the art, forexample, using transmission electron microscopy and/or physicalmodeling.

In some embodiments, the diameter of the core nanostructure is betweenabout 1 nm and about 9 nm, about 1 nm and about 8 nm, about 1 nm andabout 7 nm, about 1 nm and about 6 nm, about 1 nm and about 5 nm, about1 nm and about 4 nm, about 1 nm and about 3 nm, about 1 nm and about 2nm, about 2 nm and about 9 nm, about 2 nm and about 8 nm, about 2 nm andabout 7 nm, about 2 nm and about 6 nm, about 2 nm and about 5 nm, about2 nm and about 4 nm, about 2 nm and about 3 nm, about 3 nm and about 9nm, about 3 nm and about 8 nm, about 3 nm and about 7 nm, about 3 nm andabout 6 nm, about 3 nm and about 5 nm, about 3 nm and about 4 nm, about4 nm and about 9 nm, about 4 nm and about 8 nm, about 4 nm and about 7nm, about 4 nm and about 6 nm, about 4 nm and about 5 nm, about 5 nm andabout 9 nm, about 5 nm and about 8 nm, about 5 nm and about 7 nm, about5 nm and about 6 nm, about 6 nm and about 9 nm, about 6 nm and about 8nm, about 6 nm and about 7 nm, about 7 nm and about 9 nm, about 7 nm andabout 8 nm, or about 8 nm and about 9 nm. In some embodiments, thediameter of the core nanostructures is about 7 nm.

Nanostructure Shell Layers

In some embodiments, the nanostructures of the present disclosurecomprise a core and at least one shell. In some embodiments, thenanostructures comprise a core and at least two shells. In someembodiments, the nanostructure comprises a core and two shells.

The shell can, e.g., increase the quantum yield and/or stability of thenanostructures. In some embodiments, the core and the shell comprisedifferent materials. In some embodiments, the nanostructure comprisesshells of different shell material.

In some embodiments, a shell that comprises a mixture of Group II and VIelements is deposited onto a core or a core/shell(s) structure. In someembodiments, the shell is deposited by a mixture of at least two of azinc source, a selenium source, a sulfur source, a tellurium source, anda cadmium source. In some embodiments, the shell is deposited by amixture of two of a zinc source, a selenium source, a sulfur source, atellurium source, and a cadmium source. In some embodiments, the shellis deposited by a mixture of three of a zinc source, a selenium source,a sulfur source, a tellurium source, and a cadmium source. In someembodiments, the shell is composed of zinc and sulfur; zinc andselenium; zinc, sulfur, and selenium; zinc and tellurium; zinc,tellurium, and sulfur; zinc, tellurium, and selenium; zinc, cadmium, andsulfur; zinc, cadmium, and selenium; cadmium and sulfur; cadmium andselenium; cadmium, selenium, and sulfur; cadmium, zinc, and sulfur;cadmium, zinc, and selenium; or cadmium, zinc, sulfur, and selenium.

In some embodiments, the at least one shell comprises CdS, CdSe, CdO,CdTe, ZnS, ZnO, ZnSe, ZnTe, MgTe, GaAs, GaSb, GaN, HgO, HgS, HgSe, HgTe,InAs, InSb, InN, AlAs, AlN, AlSb, AlS, PbS, PbO, PbSe, PbTe, MgO, MgS,MgSe, MgTe, CuCl, Ge, Si, or alloys thereof. In some embodiments, the atleast one shell comprises ZnSe. In some embodiments, the at least oneshell comprises ZnS. In some embodiments, the at least one shellcomprises a first shell comprising ZnSe and a second shell comprisingZnS.

In some embodiments, a shell comprises more than one monolayer of shellmaterial. The number of monolayers is an average for all thenanostructures; therefore, the number of monolayers in a shell can be afraction. In some embodiments, the number of monolayers in a shell isbetween 0.25 and 10, 0.25 and 8, 0.25 and 7, 0.25 and 6, 0.25 and 5,0.25 and 4, 0.25 and 3, 0.25 and 2, 2 and 10, 2 and 8, 2 and 7, 2 and 6,2 and 5, 2 and 4, 2 and 3, 3 and 10, 3 and 8, 3 and 7, 3 and 6, 3 and 5,3 and 4, 4 and 10, 4 and 8, 4 and 7, 4 and 6, 4 and 5, 5 and 10, 5 and8, 5 and 7, 5 and 6, 6 and 10, 6 and 8, 6 and 7, 7 and 10, 7 and 8, or 8and 10. In some embodiments, the shell comprises between 3 and 5monolayers.

The thickness of each shell can be determined using techniques known tothose of skill in the art. In some embodiments, the thickness of eachshell is determined by comparing the average diameter of thenanostructure before and after the addition of each shell. In someembodiments, the average diameter of the nanostructure before and afterthe addition of each shell is determined by TEM.

In some embodiments, each shell has a thickness of between about 0.05 nmand about 3.5 nm, about 0.05 nm and about 2 nm, about 0.05 nm and about0.9 nm, about 0.05 nm and about 0.7 nm, about 0.05 nm and about 0.5 nm,about 0.05 nm and about 0.3 nm, about 0.05 nm and about 0.1 nm, about0.1 nm and about 3.5 nm, about 0.1 nm and about 2 nm, about 0.1 nm andabout 0.9 nm, about 0.1 nm and about 0.7 nm, about 0.1 nm and about 0.5nm, about 0.1 nm and about 0.3 nm, about 0.3 nm and about 3.5 nm, about0.3 nm and about 2 nm, about 0.3 nm and about 0.9 nm, about 0.3 nm andabout 0.7 nm, about 0.3 nm and about 0.5 nm, about 0.5 nm and about 3.5nm, about 0.5 nm and about 2 nm, about 0.5 nm and about 0.9 nm, about0.5 nm and about 0.7 nm, about 0.7 nm and about 3.5 nm, about 0.7 nm andabout 2 nm, about 0.7 nm and about 0.9 nm, about 0.9 nm and about 3.5nm, about 0.9 nm and about 2 nm, or about 2 nm and about 3.5 nm.

Ligand Exchange

U.S. Patent Appl. Publication No. 2018/0230321 discloses inks ofCdZnS/ZnS quantum dots (blue), CdZnSeS/ZnS quantum dots (green), andCdSe/CdS/ZnS quantum dots (red) that contained oleate andtrioctylphosphine ligands that were dispersed in substituted aromatic orheteroaromatic solvents such as 1-methoxynaphthalene, cyclohexylbenzene,3-isopropylbiphenyl, benzyl benzoate, 1-tetralone, or 3-phenoxytoluene.However, it was discovered that red InP/ZnSe/ZnS quantum dots comprisingorganic ligands did not completely dissolve in most of these solvents.Results of solubility testing of two different types of red InP/ZnSe/ZnSquantum dots—quantum dots comprising organic ligands and quantum dotscomprising inorganic ligands—is shown in TABLE 1.

TABLE 1 Solubility testing of red InP/ZnSe/ZnS quantum dots OrganicInorganic Solvent Ligand QD Ligand QD 1-Methylnaphthalene Turbid Turbid1-Methoxynaphthalene:Hexadecane (9:1) Clear Turbid 1-MethoxynapthaleneTurbid — 3-Phenoxytoluene Turbid Turbid Dibenzyl ether Turbid — Hexylbenzoate Turbid Turbid Octylbenzene Clear Clear Hexadecane Clear Clear

Quantum dots typically contain native organic ligands such as oleate,octanethiol, and trioctylphosphine ligands that are introduced duringthe shell synthesis. It has been found that these native ligands can beexchanged through a ligand exchange process with inorganic ligands. Inspin-coated devices, both types of quantum dots are processed from thelow-boiling point alkane solvent octane. Quantum dots comprisinginorganic ligands (after ligand exchange) show longer operating lifetimein devices containing an emissive layer and are therefore more desirablein production of an ink for use in preparing an emissive layer. A fullydispersed colloidal solution is clear, whereas a turbid mixtureindicates agglomeration of quantum dots. An ink for use in preparing anemissive layer requires that the quantum dots be fully dispersed toprevent the inkjet nozzle from clogging and to enable smooth filmformation. The solubility testing results shown in TABLE 1 show thatonly alkane (e.g., hexadecane) or alkylbenzene (e.g., octylbenzene)solvents were able to disperse both quantum dots comprising nativeorganic ligands and inorganic ligands (after ligand exchange). Inprinting tests on a Fujifilm Dimatrix DMP-2831 printer, it was foundthat a quantum dot ink prepared using only octylbenzene as solventresulted in wetting of the nozzle plate due to the relatively lowsurface tension and viscosity, and is thus not suitable as an ink.

The present disclosure is directed to a method of replacing a firstligand on a nanostructure with a second ligand. In some embodiments, thesecond ligand is an inorganic ligand. In some embodiments, thenanostructure is a quantum dot.

In some embodiments, the present disclosure is directed to a method ofreplacing a first ligand on a nanostructure with a second ligandcomprising:

-   -   admixing a reaction mixture comprising a population of        nanostructures having a first ligand bound to the nanostructure        and at least one second ligand, such that the second ligand        displaces the first ligand and becomes bound to the        nanostructure.

In some embodiments, the nanostructure is a quantum dot.

In some embodiments, the admixing is performed at a temperature betweenabout 0° C. and about 200° C., about 0° C. and about 150° C., about 0°C. and about 100° C., about 0° C. and about 80° C., about 20° C. andabout 200° C., about 20° C. and about 150° C., about 20° C. and about100° C., about 20° C. and about 80° C., about 50° C. and about 200° C.,about 50° C. and about 150° C., about 50° C. and about 100° C., about50° C. and about 80° C., about 80° C. and about 200° C., about 80° C.and about 150° C., about 80° C. and about 100° C., about 100° C. andabout 200° C., about 100° C. and about 150° C., or about 150° C. andabout 200° C. In some embodiments, the admixing is performed at atemperature between about 20° C. and about 100° C. In some embodiments,the admixing is performed at a temperature of about 22° C. In someembodiments, the admixing is performed at a temperature of about 70° C.

In some embodiments, the admixing is performed over a period of betweenabout 1 minute and about 6 hours, about 1 minute and about 2 hours,about 1 minute and about 1 hour, about 1 minute and about 40 minutes,about 1 minute and about 30 minutes, about 1 minute and about 20minutes, about 1 minute and about 10 minutes, about 10 minutes and about6 hours, about 10 minutes and about 2 hours, about 10 minutes and about1 hour, about 10 minutes and about 40 minutes, about 10 minutes andabout 30 minutes, about 10 minutes and about 20 minutes, about 20minutes and about 6 hours, about 20 minutes and about 2 hours, about 20minutes and about 1 hour, about 20 minutes and about 40 minutes, about20 minutes and about 30 minutes, about 30 minutes and about 6 hours,about 30 minutes and about 2 hours, about 30 minutes and about 1 hour,about 30 minutes and about 40 minutes, about 40 minutes and about 6hours, about 40 minutes and about 2 hours, about 40 minutes and about 1hour, about 1 hour and about 6 hours, about 1 hour and about 2 hours, orabout 2 hours and about 6 hours.

In some embodiments, the reaction mixture further comprises a solvent.In some embodiments, the solvent is selected from the group consistingof chloroform, acetone, butanone, tetrahydrofuran,2-methyltetrahydrofuran, ethylene glycol monoethyl ether, ethyleneglycol monopropyl ether, ethylene glycol monobutyl ether, diethyleneglycol diethyl ether, methyl isobutyl ketone, monomethyl ether glycolester, gamma-butyrolactone, methylacetic-3-ethyl ether, butyl carbitol,butyl carbitol acetate, propanediol monomethyl ether, propanediolmonomethyl ether acetate, cyclohexane, toluene, xylene, isopropylalcohol, N-methylformamide, and combinations thereof. In someembodiments, the solvent is toluene. In some embodiments, the solvent isN-methylformamide. In some embodiments, the solvent is a mixture oftoluene and N-methylformamide.

The percentage of second ligands that are bound to a nanostructure in apopulation of nanostructures can be measured by ¹H NMR, wherein thebound ligands are calculated using: (bound second ligands)/(bound+freesecond ligands).

In some embodiments, the mole percentage of second ligands bound to ananostructures is between about 20% and about 100%, about 20% and about80%, about 20% and about 60%, about 20% and about 40%, about 25% andabout 100%, about 25% and about 80%, about 25% and about 60%, about 25%and about 40%, about 30% and about 100%, about 30% and about 80%, about30% and about 60%, about 30% and about 40%, about 40% and about 100%,about 40% and about 80%, about 40% and about 60%, about 60% and about100%, about 60% and about 80%, or about 80% and about 100%.

First Ligands

In some embodiments, each shell is synthesized in the presence of atleast one nanostructure ligand. Ligands can, e.g., enhance themiscibility of nanostructures in solvents or polymers (allowing thenanostructures to be distributed throughout a composition such that thenanostructures do not aggregate together), increase quantum yield ofnanostructures, and/or preserve nanostructure luminescence (e.g., whenthe nanostructures are incorporated into a matrix). In some embodiments,the ligand(s) for the core synthesis and for the shell synthesis are thesame. In some embodiments, the ligand(s) for the core synthesis and forthe shell synthesis are different. Following synthesis, any ligand onthe surface of the nanostructures can be exchanged for a differentligand with other desirable properties. Examples of ligands aredisclosed in U.S. Pat. Nos. 7,572,395, 8,143,703, 8,425,803, 8,563,133,8,916,064, 9,005,480, 9,139,770, and 9,169,435, and in U.S. PatentApplication Publication No. 2008/0118755.

In some embodiments, the first ligand is a fatty acid selected from thegroup consisting of lauric acid, caproic acid, myristic acid, palmiticacid, stearic acid, and oleic acid. In some embodiments, the firstligand is an organic phosphine or an organic phosphine oxide selectedfrom trioctylphosphine oxide, trioctylphosphine, diphenylphosphine,triphenylphosphine oxide, and tributylphosphine oxide. In someembodiments, the first ligand is an amine selected from the groupconsisting of dodecylamine, oleylamine, hexadecylamine, dioctylamine,and octadecylamine. In some embodiments, the first ligand istrioctylphosphine, trioctylphosphine oxide, trihydroxypropyl phosphine,tributylphosphine, tridodecylphosphine, dibutyl phosphite, tributylphosphite, octadecyl phosphite, trilauryl phosphite, didodecylphosphite, triisodocyl phosphite, bis (2-ethylhexyl) phosphate, tridecylphosphate, hexadecylamine, oleylamine, octadecylamine, dioctadecylamine,octacosamine, bis (2-ethylhexyl) amine, octylamine, dioctylamine,trioctylamine, dodecylamine, didodecylamine, hexadecylamine, phenylphosphoric acid, hexylphosphoric acid, tetradecylphosphonic acid, octylphosphoric acid, n-octadecylphosphonic acid, propenyldiphosphonic acid,dioctyl ether, diphenyl ether, octyl mercaptan, dodecyl mercaptan,oleate, or octanethiol. In some embodiments, the first ligand is oleate,trioctylphosphine, or octanethiol.

Second Ligands

In some embodiments, the second ligand is an inorganic ligand. In someembodiments, the second ligand comprises an inorganic anion and anorganic cation.

In some embodiments, the second ligand comprises an inorganic anion. Insome embodiments, the inorganic anion comprises a metal. In someembodiments, the inorganic anion comprises a halometallate anion. Insome embodiments, the halometallate anion is a bromometallate anion, achlorometallate anion, a fluorometallate anion, or an iodometallateanion.

In some embodiments, the halometallate anion is represented by one ofFormula (I) MX₃ ⁻, Formula (II) MX_(4-x)Y_(x) ⁻, or Formula (III)MX_(4-x)Y_(x) ²⁻,

wherein:

-   -   M is selected from the group consisting of Zn, Cd, Hg, Cu, Ag,        and Au;    -   X is selected from the group consisting of Br, Cl, F, and I;    -   Y is selected from the group consisting of Br, Cl, F, and I; and    -   x is 0, 1, or 2.

In some embodiments, the halometallate anion is a halozincate anion. Insome embodiments, the halozincate anion is a ZnBr₃ ⁻ anion, a ZnCl₃ ⁻anion, a ZnF₃ ⁻ anion, a ZnI₃ ⁻ anion, a ZnBr₄ ² anion, a ZnCl₄ ²⁻anion, a ZnF₄ ² anion, a ZnI₄ ² anion, or a ZnCl₂F₂ ²⁻ anion.

In some embodiments, the second ligand comprises an organic cation. Insome embodiments, the organic cation is selected from the groupconsisting of a tetraalkylammonium cation, an alkylphosphonium cation, aformamidinium cation, a guanidinium cation, an imidazolium cation, and apyridinium cation.

In some embodiments, the organic cation is a tetraalkylammonium cationand is selected from the group consisting ofdioctadecyldimethylammonium, dihexadecyldimethylammonium,ditetradecyldimethylammonium, didodecyldimethylammonium,didecyldimethylammonium, dioctyldimethylammonium,bis(ethylhexyl)dimethylammonium, octadecyltrimethylammonium,oleyltrimethylammonium, hexadecyltrimethylammonium,tetradecyltrimethylammonium, dodecyltrimethylammonium,decyltrimethylammonium, octyltrimethylammonium,phenylethyltrimethylammonium, benzyltrimethylammonium,phenyltrimethylammonium, benzylhexadecyldimethylammonium,benzyltetradecyldimethylammonium, benzyldodecyldimethylammonium,benzyldecyldimethylammonium, benzyloctyldimethylammonium,benzyltributylammonium, benzyltriethylammonium, tetrabutylammonium,tetrapropylammonium, diisopropyldimethylammonium, tetraethylammonium,and tetramethylammonium. In some embodiments, the organic cation isdidecyldimethylammonium. In some embodiments, the organic cation istetrabutylammonium.

In some embodiments, the organic cation is an alkylphosphonium cationand is selected from the group consisting of tetraphenylphosphonium,dimethyldiphenylphosphonium, methyltriphenoxyphosphonium,hexadecyltributylphosphonium, octyltributylphosphonium,tetradecyltrihexylphosphonium, tetrakis(hydroxymethyl)phosphonium,tetraoctylphosphonium, tetrabutylphosphonium, andtetramethylphosphonium.

In some embodiments, the organic cation is a guanidinium cation. In someembodiments, the guanidinium cation is N,N,N′,N′,N″,N″-hexaalkylguanidinium.

In some embodiments, the organic cation is an imidazolium cation. Insome embodiments, the imidazolium cation is 1,3-dialkyl imidazolium or1,2,3-trialkyl imidazolium.

In some embodiments, the organic cation is a pyridinium cation. In someembodiments, the pyridinium cation is N-alkyl pyridinium.

In some embodiments, the inorganic ligand is tetrabutylammoniumtetrafluorozincate or tetrabutylammonium dichlorodifluorozincate.

Organic Solvents

Solvents suitable for inkjet printing of electroluminescent quantum dotlight emitting diodes are known to those of skill in the art. In someembodiments, the organic solvent is a substituted aromatic orheteroaromatic solvent described in U.S. Patent Appl. Publication No.2018/0230321, which is incorporated herein by reference in its entirety.

In some embodiments, the organic solvent used in a nanostructurecomposition used as an inkjet printing formulation is defined by itsboiling point, viscosity, and surface tension. Properties of organicsolvents suitable for inkjet printing formulations are shown in TABLE 2.

TABLE 2 Properties of organic solvents for inkjet printing formulationsBoiling Point Viscosity Surface tension Solvent (° C.) (mPa · s)(dyne/cm) 1-Methylnaphthalene 240 3.3 38 1-Methoxynaphthalene 270 7.2 433-Phenoxytoluene 271 4.8 37 Dibenzyl ether 298 8.7 39 Benzyl benzoate324 10.0  44 Butyl benzoate 249 2.7 34 Hexyl benzoate 272 — —Octylbenzene 265 2.6 31 Cyclohexylbenzene 240 2.0 34 Hexadecane 287 3.428 4-Methylanisole 179 — 29

In some embodiments, the organic solvent has a boiling point at 1atmosphere of between about 150° C. and about 350° C. In someembodiments the organic solvent has a boiling point at 1 atmosphere ofbetween about 150° C. and about 350° C., about 150° C. and about 300°C., about 150° C. and about 250° C., about 150° C. and about 200° C.,about 200° C. and about 350° C., about 200° C. and about 300° C., about200° C. and about 250° C., about 250° C. and about 350° C., about 250°C. and about 300° C., or about 300° C. and about 350° C.

In some embodiments, the organic solvent has a viscosity between about 1mPa's and about 15 mPa's. In some embodiments, the organic solvent has aviscosity between about 1 mPa's and about 15 mPa's, about 1 mPa's andabout 10 mPa's, about 1 mPa's and about 8 mPa's, about 1 mPa's and about6 mPa's, about 1 mPa's and about 4 mPa's, about 1 mPa's and about 2mPa's, about 2 mPa's and about 15 mPa's, about 2 mPa's and about 10mPa's, about 2 mPa's and about 8 mPa's, about 2 mPa's and about 6 mPa's,about 2 mPa's and about 4 mPa's, about 4 mPa's and about 15 mPa's, about4 mPa's and about 10 mPa's, about 4 mPa's and about 8 mPa's, about 4mPa's and about 6 mPa's, about 6 mPa's and about 15 mPa's, about 6 mPa'sand about 10 mPa's, about 6 mPa's and about 8 mPa's, about 8 mPa's andabout 15 mPa's, about 8 mPa's and about 10 mPa's, or about 10 mPa's andabout 15 mPa's.

In some embodiments, the organic solvent has a surface tension ofbetween about 20 dyne/cm and about 50 dyne/cm. In some embodiments, theorganic solvent has a surface tension of between about 20 dyne/cm andabout 50 dyne/cm, about 20 dyne/cm and about 40 dyne/cm, about 20dyne/cm and about 35 dyne/cm, about 20 dyne/cm and about 30 dyne/cm,about 20 dyne/cm and about 25 dyne/cm, about 25 dyne/cm and about 50dyne/cm, about 25 dyne/cm and about 40 dyne/cm, about 25 dyne/cm andabout 35 dyne/cm, about 25 dyne/cm and about 30 dyne/cm, about 30dyne/cm and about 50 dyne/cm, about 30 dyne/cm and about 40 dyne/cm,about 30 dyne/cm and about 35 dyne/cm, about 35 dyne/cm and about 50dyne/cm, about 35 dyne/cm and about 40 dyne/cm, or about 40 dyne/cm andabout 50 dyne/cm.

In some embodiments, the organic solvent used in the nanostructurecomposition is an alkylnaphthalene, an alkoxynaphthalene, analkylbenzene, an aryl, an alkyl-substituted benzene, acycloalkylbenzene, a C₉-C₂₀ alkane, a diarylether, an alkyl benzoate, anaryl benzoate, or an alkoxy-substituted benzene.

In some embodiments, the organic solvent used in a nanostructurecomposition is 1-tetralone, 3-phenoxytoluene, acetophenone,1-methoxynaphthalene, n-octylbenzene, n-nonylbenzene, 4-methylanisole,n-decylbenzene, p-diisopropylbenzene, pentylbenzene, tetralin,cyclohexylbenzene, chloronaphthalene, 1,4-dimethylnaphthalene,3-isopropylbiphenyl, p-methylcumene, dipentylbenzene, o-diethylbenzene,m-diethylbenzene, p-diethylbenzene, 1,2,3,4-tetramethylbenzene,1,2,3,5-tetramethylbenzene, 1,2,4,5-tetrametylbenzene, butylbenzene,dodecylbenzene, 1-methylnaphthalene, 1,2,4-trichlorobenzene, diphenylether, diphenylmethane, 4-isopropylbiphenyl, benzyl benzoate,1,2-bi(3,4-dimethylphenyl)ethane, 2-isopropylnaphthalene, dibenzylether, or a combination thereof. In some embodiments, the organicsolvent used in a nanostructure composition is 1-methylnaphthalene,n-octylbenzene, 1-methoxynapththalene, 3-phenoxytoluene,cyclohexylbenzene, 4-methylanisole, n-decylbenzene, or a combinationthereof.

In some embodiments, the organic solvent is an anhydrous organicsolvent. In some embodiments, the organic solvent is a substantiallyanhydrous organic solvent.

In some embodiments, the weight percentage of organic solvent in thenanostructure composition is between about 70% and about 99%. In someembodiments, the weight percentage of organic solvent in thenanostructure composition is between about 70% and about 99%, about 70%and about 98%, about 70% and about 95%, about 70% and about 90%, about70% and about 85%, about 70% and about 80%, about 70% and about 75%,about 75% and about 99%, about 75% and about 98%, about 75% and about95%, about 75% and about 90%, about 75% and about 85%, about 75% andabout 80%, about 80% and about 99%, about 80% and about 98%, about 80%and about 95%, about 80% and about 90%, about 80% and about 85%, about85% and about 99%, about 85% and about 98%, about 85% and about 95%,about 85% and about 90%, about 90% and about 99%, about 90% and about98%, about 90% and about 95%, about 95% and about 99%, about 95% andabout 98%, or about 98% and about 99%. In some embodiments, the weightpercentage of organic solvent in the nanostructure composition isbetween about 95% and about 99%.

Poly(Alkene Oxide) Additive

In some embodiments, a poly(alkylene oxide) additive comprises apoly(alkylene oxide) backbone. In some embodiments, the poly(alkyleneoxide) additive comprises at least one functional group attached to thepoly(alkylene oxide) backbone. In some embodiments, the at least onefunctional group can bind to II-VI nanocrystal surfaces as a neutralL-type binding ligand (e.g., R—COOH). In some embodiments, the at leastone functional group can bind to II-VI nanocrystal surfaces as anelectron donating X-type ligand (e.g., R-000).

In some embodiments, the poly(alkylene oxide) additive has at least onefunctional group. In some embodiments, the at least one functional groupis —OH, —NH₂, —NH₃ ⁺, —N₃, —C(═O)OR³, —P(═O)(OR⁴)₃, or —P(R⁵)₄.

In some embodiments, the poly(alkylene oxide) additive is a mixture of afunctional group terminated poly(alkylene oxide), a copolymer ofalkylene oxides, and combinations thereof. In some embodiments, thefunctional group terminated poly(alkylene oxide) comprises a copolymerof alkylene oxides. In some embodiments, the copolymer is a randomcopolymer or a block copolymer. In some embodiments, the block copolymeris a diblock copolymer or a triblock copolymer. In some embodiments, thecopolymer is based on a propylene oxide (PO), an ethylene oxide (EO), ora mixture of PO and EO. In some embodiments, the copolymer is a mixtureof PO and EO.

In some embodiments, the poly(alkylene oxide) additive comprises arandom copolymer of ethylene oxide and propylene oxide, a poly(ethyleneoxide)-poly(propylene oxide) diblock copolymer, a poly(ethyleneoxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer, apoly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide)triblock copolymer, or combinations thereof.

In some embodiments, the poly(alkylene oxide) additive comprises acopolymer of PO and EO. In some embodiments, the ratio of ethylene oxidegroups to propylene oxide groups is sufficiently high so that thepoly(alkylene oxide) ligand has a high degree of hydrophilicity. In someembodiments, the ratio of ethylene oxide groups to propylene oxidegroups is low enough that the ligand has the desired resiliency. In someembodiments, the ratio of ethylene oxide groups:propylene oxide groupsis between about 15:1 and about 1:15, about 15:1 and about 1:10, about15:1 and about 1:5, about 10:1 and 1:15, about 10:1 and 1:10, about 10:1and 1:5, about 5:1 and 1:15, about 5:1 and 1:10, or about 5:1 and 1:5.

In some embodiments, the poly(alkylene oxide) additive has the structureof Formula IV:

wherein:

-   -   x is 1 to 100;    -   y is 0 to 100;    -   R^(1A) and R^(1B) independently are H or C₁₋₂₀ alkyl;    -   R² is C₁₋₂₀ alkyl;    -   X₁ is a bond or C₁₋₁₂ alkyl;    -   X₂ is a bond, —O—, —OC(═O)—, or amido;    -   FG is —OH, —NH₂, —NH₄ ⁺, —N₃, —C(═O)OR³, —P(═O)(OR⁴)₃, or        —P(R⁵)₄;    -   R³ is H, C₁₋₂₀ alkyl, or C₆₋₁₄ aryl;    -   R⁴ is independently H, C₁₋₂₀ alkyl, or C₆₋₁₄ aryl; and    -   R⁵ is independently H, C₁₋₂₀ alkyl or C₆₋₁₄ aryl.

In some embodiments, x is 1 to 100, 1 to 50, 1 to 20, 1 to 10, 1 to 5, 5to 100, 5 to 50, 5 to 20, 5 to 10, 10 to 100, 10 to 50, 10 to 20, 20 to100, 20 to 50, or 50 to 100. In some embodiments, x is 10 to 50. In someembodiments, x is 10 to 20. In some embodiments, x is 1. In someembodiments, x is 19. In some embodiments, x is 6. In some embodiments,x is 10.

The values for x are to be understood as modified by the word “about.”Therefore, a value of x=1 is understood to mean x=1±0.1. For example avalue of x=1 is understood to mean 0.9 to 1.1.

In some embodiments, y is 1 to 100, 1 to 50, 1 to 20, 1 to 10, 1 to 5, 5to 100, 5 to 50, 5 to 20, 5 to 10, 10 to 100, 10 to 50, 10 to 20, 20 to100, 20 to 50, or 50 to 100. In some embodiments, y is 1 to 30. In someembodiments, y is 1 to 10. In some embodiments, y is 9. In someembodiments, y is 3. In some embodiments, y is 29. In some embodiments,y is 10.

The values for y are to be understood as modified by the word “about.”Therefore, a value of y=1 is understood to mean y=1±0.1. For example avalue of y=1 is understood to mean 0.9 to 1.1.

In some embodiments, the ratio of x to y is between about 15:1 and about1:15, about 15:1 and about 1:10, about 15:1 and about 1:5, about 10:1and about 1:15, about 10:1 and about 1:10, about 10:1 and about 1:5,about 5:1 and about 1:15, about 5:1 and about 1:10, or about 5:1 andabout 1:5. In some embodiments, the ratio of x toy is about 1:9. In someembodiments, the ratio of x toy is about 19:3. In some embodiments, theratio of x to y is about 6:29. In some embodiments, the ratio of x to yis about 31:10.

In some embodiments, R^(1A) is H. In some embodiments, R^(1A) is C₁₋₂₀alkyl. In some embodiments, R^(1A) is C₁₋₁₀ alkyl. In some embodiments,R^(1A) is C₁₋₂₀ alkyl. In some embodiments, R^(1A) is —CH₃.

In some embodiments, R^(1B) is H. In some embodiments, R^(1B) is C₁₋₂₀alkyl. In some embodiments, R^(1B) is C₁₋₁₀ alkyl. In some embodiments,R^(1B) is C₁₋₅ alkyl. In some embodiments, R^(1B) is —CH₃.

In some embodiments, R^(1A) is H and R^(1B) are —CH₃. In someembodiments, R^(1A) is

-   -   CH₃ and R^(1B) is H. In some embodiments, R^(1A) is H and R^(1B)        is H. In some embodiments, R^(1A) is —CH₃ and R^(1B) is —CH₃.

In some embodiments, R² is C₁₋₂₀ alkyl. In some embodiments, R² is C₁₋₁₀alkyl. In some embodiments, R² is C₁₋₂₀ alkyl. In some embodiments, R²is —CH₂CH₃.

In some embodiments, X₁ is a bond. In some embodiments, X₁ is C₁₋₁₂alkyl.

In some embodiments, X₂ is a bond. In some embodiments, X₂ is —OC(═O)—.In some embodiments, X₂ is amido.

In some embodiments, FG is —OH. In some embodiments, FG is —NH₂. In someembodiments, FG is —NH₄ ⁺. In some embodiments, FG is —N₃. In someembodiments, FG is —C(═O)OR³. In some embodiments, FG is —P(═O)(OR⁴)₃.In some embodiments, FG is —P(R⁵)₄.

In some embodiments, R³ is H. In some embodiments, R³ is C₁₋₂₀ alkyl. Insome embodiments, R³ is C₁₋₁₀ alkyl. In some embodiments, R³ is C₁₋₅alkyl. In some embodiments, R³ is —CH₃. In some embodiments, R³ is C₃₋₈cycloalkyl. In some embodiments, R³ is C₆₋₁₄ aryl. In some embodiments,R³ is phenyl, naphthyl, phenanthryl, anthracyl, indenyl, azulenyl,biphenyl, biphenylenyl, or fluorenyl.

In some embodiments, R⁴ is H. In some embodiments, R⁴ is C₁₋₂₀ alkyl. Insome embodiments, R⁴ is C₁₋₁₀ alkyl. In some embodiments, R⁴ is C₁₋₂₀alkyl. In some embodiments, R⁴ is —CH₃. In some embodiments, R⁴ is C₃₋₈cycloalkyl. In some embodiments, R⁴ is C₆₋₁₄ aryl. In some embodiments,R⁴ is phenyl, naphthyl, phenanthryl, anthracyl, indenyl, azulenyl,biphenyl, biphenylenyl, or fluorenyl.

In some embodiments, R⁵ is H. In some embodiments, R⁵ is C₁₋₂₀ alkyl. Insome embodiments, R⁵ is C₁₋₁₀ alkyl. In some embodiments, R⁵ is C₁₋₂₀alkyl. In some embodiments, R⁵ is —CH₃. In some embodiments, R⁵ is C₃₋₈cycloalkyl. In some embodiments, R⁵ is C₆₋₁₄ aryl. In some embodiments,R⁵ is phenyl, naphthyl, phenanthryl, anthracyl, indenyl, azulenyl,biphenyl, biphenylenyl, or fluorenyl.

In some embodiments, wherein R^(1A) is H and FG is —NH₂ in Formula IV,the poly(alkylene oxide) ligand has the structure of Formula V:

wherein:

-   -   x is 1 to 100;    -   y is 0 to 100;    -   X₁ is a bond or C₁₋₁₂ alkylene;    -   X₂ is a bond, —O—, —OC(═O)—, or amido;    -   R^(1B) is H or C₁₋₂₀ alkyl; and

R² is C₁₋₂₀ alkyl.

In some embodiments, x is 1 to 100, 1 to 50, 1 to 20, 1 to 10, 1 to 5, 5to 100, 5 to 50, 5 to 20, 5 to 10, 10 to 100, 10 to 50, 10 to 20, 20 to100, 20 to 50, or 50 to 100. In some embodiments, y is 1 to 100, 1 to50, 1 to 20, 1 to 10, 1 to 5, 5 to 100, 5 to 50, 5 to 20, 5 to 10, 10 to100, 10 to 50, 10 to 20, 20 to 100, 20 to 50, or 50 to 100.

In some embodiments, the ratio of x to y is between about 15:1 and about1:15, about 15:1 and about 1:10, about 15:1 and about 1:5, about 10:1and 1:15, about 10:1 and 1:10, about 10:1 and 1:5, about 5:1 and 1:15,about 5:1 and 1:10, or about 5:1 and 1:5.

In some embodiments, R^(1B) is H. In some embodiments, R^(1B) is C₁₋₂₀alkyl. In some embodiments, R^(1B) is C₁₋₁₀ alkyl. In some embodiments,R^(1B) is C₁₋₅ alkyl. In some embodiments, R^(1B) is —CH₃.

In some embodiments, R² is C₁₋₂₀ alkyl. In some embodiments, R² is C₁₋₁₀alkyl.

In some embodiments, R² is C₁₋₂₀ alkyl. In some embodiments, R² is—CH₂CH₃.

In some embodiments, X₁ is a bond. In some embodiments, X₁ is C₁₋₁₂alkyl.

In some embodiments, X₂ is a bond. In some embodiments, X₂ is —OC(═O)—.In some embodiments, X₂ is amido.

In some embodiments, wherein R^(1A) is H, R^(1B) is —CH₃, X₁ is a bond,X₂ is a bond, and FG is —NH₂ in Formula IV, the poly(alkylene oxide)ligand has the structure of Formula VI:

wherein:

-   -   x is 1 to 100;    -   y is 0 to 100; and    -   R² is C₁₋₂₀ alkyl.

In some embodiments, x is 1 to 100, 1 to 50, 1 to 20, 1 to 10, 1 to 5, 5to 100, 5 to 50, 5 to 20, 5 to 10, 10 to 100, 10 to 50, 10 to 20, 20 to100, 20 to 50, or 50 to 100. In some embodiments, x is 10 to 50. In someembodiments, x is 10 to 20. In some embodiments, x is 1. In someembodiments, x is 19. In some embodiments, x is 6. In some embodiments,x is 10.

In some embodiments, R² is C₁₋₂₀ alkyl. In some embodiments, R² is C₁₋₁₀alkyl. In some embodiments, R² is C₁₋₅ alkyl. In some embodiments, R² is—CH₂CH₃.

In some embodiments, the amine-terminated polymer is a commerciallyavailable amine-terminated polymer from Huntsman PetrochemicalCorporation. In some embodiments, the amine-terminated polymer offormula (VI) has x=1, y=9, and R²=—CH₃ and is JEFFAMINE M-600 (HuntsmanPetrochemical Corporation, Texas.). JEFFAMINE M-600 has a molecularweight of approximately 600. In some embodiments, the amine-terminatedpolymer of formula (III) has x=19, y=3, and R²=—CH₃ and is JEFFAMINEM-1000 (Huntsman Petrochemical Corporation, Texas.). JEFFAMINE M-1000has a molecular weight of approximately 1,000. In some embodiments, theamine-terminated polymer of formula (III) has x=6, y=29, and R²=—CH₃ andis JEFFAMINE M-2005 (Huntsman Petrochemical Corporation, Texas.).JEFFAMINE M-2005 has a molecular weight of approximately 2,000. In someembodiments, the amine-terminated polymer of formula (III) has x=31,y=10, and R²=—CH₃ and is JEFFAMINE M-2070 (Huntsman PetrochemicalCorporation, Texas.). JEFFAMINE M-2070 has a molecular weight ofapproximately 2,000.

In some embodiments, wherein R^(1A) is H and FG is —N₃ in Formula IV,the poly(alkylene oxide) ligand has the structure of Formula VII:

wherein:

-   -   x is 1 to 100;    -   y is 0 to 100;    -   X₁ is a bond or C₁₋₁₂ alkyl;    -   X₂ is a bond, —O—, —OC(═O)—, or amido; and    -   R² is C₁₋₂₀ alkyl.

In some embodiments, x is 1 to 100, 1 to 50, 1 to 20, 1 to 10, 1 to 5, 5to 100, 5 to 50, 5 to 20, 5 to 10, 10 to 100, 10 to 50, 10 to 20, 20 to100, 20 to 50, or 50 to 100. In some embodiments, y is 1 to 100, 1 to50, 1 to 20, 1 to 10, 1 to 5, 5 to 100, 5 to 50, 5 to 20, 5 to 10, 10 to100, 10 to 50, 10 to 20, 20 to 100, 20 to 50, or 50 to 100.

In some embodiments, R² is C₁₋₂₀ alkyl. In some embodiments, R² is C₁₋₁₀alkyl. In some embodiments, R² is C₁₋₅ alkyl. In some embodiments, R² is—CH₂CH₃.

In some embodiments, X₁ is a bond. In some embodiments, X₁ is C₁₋₁₂alkyl.

In some embodiments, X₂ is a bond. In some embodiments, X₂ is —OC(═O)—.In some embodiments, X₂ is amido.

In some embodiments, wherein R^(1A) is —H, R^(1B) is —H, X₁ is a bond,X₂ is a bond, and FG is —N₃ in Formula IV, the poly(alkylene oxide)ligand has the structure of Formula VIII:

wherein:

-   -   x is 1 to 100;    -   y is 0 to 100; and    -   R² is C₁₋₂₀ alkyl.

In some embodiments, x is 1 to 100, 1 to 50, 1 to 20, 1 to 10, 1 to 5, 5to 100, 5 to 50, 5 to 20, 5 to 10, 10 to 100, 10 to 50, 10 to 20, 20 to100, 20 to 50, or 50 to 100. 1. In some embodiments, x is 19. In someembodiments, x is 6. In some embodiments, x is 10.

In some embodiments, R² is C₁₋₂₀ alkyl. In some embodiments, R² is C₁₋₁₀alkyl. In some embodiments, R² is C₁₋₅ alkyl. In some embodiments, R² is—CH₂CH₃.

In some embodiments, the azide-terminated polymer is a commerciallyavailable azide-terminated polymer available from Sigma-Aldrich such asmethoxypolyethylene glycol azide (average Mn=2000 (wherein y=1)),methoxypolyethylene glycol azide (average Mn=10,000 (wherein y=1)),methoxypolyethylene glycol azide (average Mn=2000 (wherein y=1)),O-(2-(azidoethyl)-O′-methyl-triethylene glycol (wherein x=3, y=1),O-(2-(azidoethyl)-O′-methyl-undecaethylene glycol (wherein x=11, y=1),O-(2-(azidoethyl)-O′-methyl-nonaethylene glycol (wherein x=19, y=1),poly(ethylene glycol) methyl ether azide (average Mn=400 (wherein y=1)),or poly(ethylene glycol) methyl ether azide (average Mn=1,000 (whereiny=1)).

In some embodiments, wherein R^(1A) is —H and FG is —CO₂H in Formula IV,the poly(alkylene oxide) ligand has the structure of Formula IX:

wherein:

-   -   x is 1 to 100;    -   y is 0 to 100;    -   X₁ is a bond or C₁₋₁₂ alkyl;    -   X₂ is a bond, —O—, —OC(═O)—, or amido; and R² is C₁₋₂₀ alkyl.

In some embodiments, x is 1 to 100, 1 to 50, 1 to 20, 1 to 10, 1 to 5, 5to 100, 5 to 50, 5 to 20, 5 to 10, 10 to 100, 10 to 50, 10 to 20, 20 to100, 20 to 50, or 50 to 100. In some embodiments, y is 1 to 100, 1 to50, 1 to 20, 1 to 10, 1 to 5, 5 to 100, 5 to 50, 5 to 20, 5 to 10, 10 to100, 10 to 50, 10 to 20, 20 to 100, 20 to 50, or 50 to 100.

In some embodiments, R² is C₁₋₂₀ alkyl. In some embodiments, R² is C₁₋₁₀alkyl. In some embodiments, R² is C₁₋₅ alkyl. In some embodiments, R² is—CH₂CH₃.

In some embodiments, X₁ is a bond. In some embodiments, X₁ is C₁₋₁₂alkyl.

In some embodiments, X₂ is a bond. In some embodiments, X₂ is —OC(═O)—.In some embodiments, X₂ is amido.

In some embodiments, wherein R^(1A) is —H, R^(1B) is —H, X₁ is a bond,X₂ is a bond, and FG is —CO₂H in Formula IV, the poly(alkylene oxide)ligand has the structure of Formula X:

wherein:

-   -   x is 1 to 100;    -   y is 0 to 100; and    -   R² is C₁₋₂₀ alkyl.

In some embodiments, x is 1 to 100, 1 to 50, 1 to 20, 1 to 10, 1 to 5, 5to 100, 5 to 50, 5 to 20, 5 to 10, 10 to 100, 10 to 50, 10 to 20, 20 to100, 20 to 50, or 50 to 100. In some embodiments, y is 1 to 100, 1 to50, 1 to 20, 1 to 10, 1 to 5, 5 to 100, 5 to 50, 5 to 20, 5 to 10, 10 to100, 10 to 50, 10 to 20, 20 to 100, 20 to 50, or 50 to 100.

In some embodiments, R² is C₁₋₂₀ alkyl. In some embodiments, R² is C₁₋₁₀alkyl. In some embodiments, R² is C₁₋₅ alkyl. In some embodiments, R² is—CH₂CH₃.

In some embodiments, the carboxylic acid-terminated polymer of Formula Xis a commercially available carboxylic acid-terminated polymer availablefrom Sigma-Aldrich such as methoxypolyethylene glycol propionic acid(average Mn=5,000 (wherein y=1).

In some embodiments, wherein R^(1A) is —H and FG is —OH in Formula IV,the poly(alkylene oxide) ligand has the structure of Formula XI:

wherein:

-   -   x is 1 to 100;    -   y is 0 to 100;    -   X₁ is a bond or C₁₋₁₂ alkyl;    -   X₂ is a bond, —O—, —OC(═O)—, or amido; and    -   R² is C₁₋₂₀ alkyl.

In some embodiments, x is 1 to 100, 1 to 50, 1 to 20, 1 to 10, 1 to 5, 5to 100, 5 to 50, 5 to 20, 5 to 10, 10 to 100, 10 to 50, 10 to 20, 20 to100, 20 to 50, or 50 to 100. In some embodiments, y is 1 to 100, 1 to50, 1 to 20, 1 to 10, 1 to 5, 5 to 100, 5 to 50, 5 to 20, 5 to 10, 10 to100, 10 to 50, 10 to 20, 20 to 100, 20 to 50, or 50 to 100.

In some embodiments, R² is C₁₋₂₀ alkyl. In some embodiments, R² is C₁₋₁₀alkyl. In some embodiments, R² is C₁₋₅ alkyl. In some embodiments, R² is—CH₂CH₃.

In some embodiments, X₁ is a bond. In some embodiments, X₁ is C₁₋₁₂alkyl.

In some embodiments, X₂ is a bond. In some embodiments, X₂ is —OC(═O)—.In some embodiments, X₂ is amido.

In some embodiments, wherein R^(1A) is —H, R^(1B) is —H, X₁ is a bond,X₂ is a bond, and FG is —OH in Formula IV, the poly(alkylene oxide)ligand has the structure of Formula XII:

wherein:

-   -   x is 1 to 100;    -   y is 0 to 100; and    -   R² is C₁₋₂₀ alkyl.

In some embodiments, x is 1 to 100, 1 to 50, 1 to 20, 1 to 10, 1 to 5, 5to 100, 5 to 50, 5 to 20, 5 to 10, 10 to 100, 10 to 50, 10 to 20, 20 to100, 20 to 50, or 50 to 100. In some embodiments, y is 1 to 100, 1 to50, 1 to 20, 1 to 10, 1 to 5, 5 to 100, 5 to 50, 5 to 20, 5 to 10, 10 to100, 10 to 50, 10 to 20, 20 to 100, 20 to 50, or 50 to 100.

In some embodiments, R² is C₁₋₂₀ alkyl. In some embodiments, R² is C₁₋₁₀alkyl.

In some embodiments, R² is C₁₋₅ alkyl. In some embodiments, R² is—CH₂CH₃.

In some embodiments, the hydroxy-terminated polymer of Formula XII is acommercially available hydroxy-terminated polymer available fromSigma-Aldrich such as poly(ethylene glycol)methyl ether (average Mn=550(wherein y=1), poly(ethylene glycol)methyl ether (average Mn=750(wherein y=1), poly(ethylene glycol)methyl ether (average Mn=5,000(wherein y=1), or poly(ethylene glycol)methyl ether (average Mn=10,000(wherein y=1).

In some embodiments, the weight percentage of poly(alkylene oxide)additive in the nanostructure composition is between about 0.05% andabout 2%. In some embodiments, the weight percentage of poly(alkyleneoxide) additive in the nanostructure composition is between about 0.05%and about 2%, about 0.05% and about 1.5%, about 0.05% and about 1%,about 0.05% and about 0.5%, about 0.05% and about 0.1%, about 0.1% andabout 2%, about 0.1% and about 1.5%, about 0.1% and about 1%, about 0.1%and about 0.5%, about 0.5% and about 2%, about 0.5% and about 1.5%,about 0.5% and about 1%, about 1% and about 2%, about 1% and about 1.5%,or about 1.5% and about 2%. In some embodiments, the weight percentageof nanostructures in the nanostructure composition is between about 0.1%and about 0.5%.

Nanostructure Compositions

In some embodiments, the nanostructure composition further comprises oneor more additional components such as surface-active compounds,lubricating agents, wetting agents, dispersing agents, hydrophobingagents, adhesive agents, flow improvers, defoaming agents, deaerators,diluents, auxiliaries, colorants, dyes, pigments, sensitizers,stabilizers, antioxidants, viscosity modifiers, and inhibitors.

In some embodiments, the nanostructure composition described herein isused in the formulation of an electronic device. In some embodiments,the nanostructure composition described herein is used in theformulation of an electronic device selected from the group consistingof a nanostructure film, a display device, a lighting device, abacklight unit, a color filter, a surface light-emitting device, anelectrode, a magnetic memory device, and a battery. In some embodiments,the nanostructure composition described herein is used in theformulation of a light-emitting device.

Provided is a process comprising depositing the nanostructurecomposition to form a layer on a substrate. In some embodiments, thedepositing is by inkjet printing. In some embodiments, the processfurther comprises at least partial removal of the substantiallyanhydrous organic solvent. In some embodiments, the at least partialremoval of the substantially anhydrous organic solvent comprises airdrying. In some embodiments, the at least partial removal of thesubstantially anhydrous organic solvent comprises application of heat.In some embodiments, the substrate is a first conductive layer. In someembodiments, the process further comprises depositing a secondconductive layer on the nanostructure composition. In some embodiments,the process further comprises depositing a first transport layer on thefirst conductive layer, the first transport layer being configured tofacilitate the transport of holes from the first conductive layer to thelayer comprising the nanostructure composition; and depositing a secondtransport layer on the layer comprising the nanostructure composition,the second transport layer configured to facilitate the transport ofelectrons from the second conductive layer to the layer comprising thenanostructure composition. In some embodiments, the nanostructurecomposition is deposited in a pattern.

Nanostructure Molded Article

In some embodiments, the nanostructure composition is used to form ananostructure molded article. In some embodiments, the nanostructuremolded article is a liquid crystal display (LCD) or a light emittingdiode (LED). In some embodiments, the nanostructure composition is usedto form the emitting layer of an illumination device. The illuminationdevice can be used in a wide variety of applications, such as flexibleelectronics, touchscreens, monitors, televisions, cellphones, and anyother high definition displays. In some embodiments, the illuminationdevice is a light emitting diode or a liquid crystal display. In someembodiments, the illumination device is a quantum dot light emittingdiode (QLED). An example of a QLED is disclosed in U.S. patentapplication Ser. No. 15/824,701, which is incorporated herein byreference in its entirety.

In some embodiments, the present disclosure provides a light emittingdiode comprising:

-   -   (a) a first conductive layer;    -   (b) a second conductive layer; and    -   (c) an emitting layer between the first conductive layer and the        second conductive layer, wherein the emitting layer comprises at        least one population of nanostructures, wherein the        nanostructures comprise (i) at least one organic solvent; (ii)        at least one nanostructure comprising a core and at least one        shell, wherein the nanostructure comprises inorganic ligands        bound to the surface of the nanostructure; and (iii) at least        one poly(alkylene oxide) additive.

In some embodiments, the present disclosure provides a light emittingdiode comprising:

-   -   (a) a first conductive layer;    -   (b) a second conductive layer; and    -   (c) an emitting layer between the first conductive layer and the        second conductive layer, wherein the emitting layer comprises at        least one population of nanostructures, wherein the        nanostructures comprise (i) at least one organic solvent; (ii)        at least one nanostructure comprising a core and at least one        shell, wherein the nanostructure comprises inorganic ligands        bound to the surface of the nanostructure, wherein the inorganic        ligands comprise a halometallate anion and an organic cation;        and (iii) at least one poly(alkylene oxide) additive.

In some embodiments, the emitting layer is a nanostructure film.

In some embodiments, the light emitting diode comprises a firstconductive layer, a second conductive layer, and an emitting layer,wherein the emitting layer is arranged between the first conductivelayer and the second conductive layer. In some embodiments, the emittinglayer is a thin film.

In some embodiments, the light emitting diode comprises additionallayers between the first conductive layer and the second conductivelayer such as a hole injection layer, a hole transport layer, and anelectron transport layer. In some embodiments, the hole injection layer,the hole transport layer, and the electron transport layer are thinfilms. In some embodiments, the layers are stacked on a substrate.

When voltage is applied to the first conductive layer and the secondconductive layer, holes injected at the first conductive layer move tothe emitting layer via the hole injection layer and/or the holetransport layer, and electrons injected from the second conductive layermove to the emitting layer via the electron transport layer. The holesand electrons recombine in the emitting layer to generate excitons.

Making a Nanostructure Layer

In some embodiments, the nanostructure layer can be embedded in apolymeric matrix. As used herein, the term “embedded” is used toindicate that the nanostructure population is enclosed or encased withthe polymer that makes up the majority of the components of the matrix.In some embodiments, at least one nanostructure population is suitablyuniformly distributed throughout the matrix. In some embodiments, the atleast one nanostructure population is distributed according to anapplication-specific distribution. In some embodiments, thenanostructures are mixed in a polymer and applied to the surface of asubstrate.

In some embodiments, a nanostructure composition is deposited to form ananostructure layer. In some embodiments, a nanostructure compositioncan be deposited by any suitable method known in the art, including butnot limited to painting, spray coating, solvent spraying, wet coating,adhesive coating, spin coating, tape-coating, roll coating, flowcoating, inkjet vapor jetting, drop casting, blade coating, mistdeposition, or a combination thereof. In some embodiments, ananostructure composition can be deposited by inkjet printing.

The nanostructure composition can be coated directly onto the desiredlayer of a substrate. Alternatively, the nanostructure composition canbe formed into a solid layer as an independent element and subsequentlyapplied to the substrate. In some embodiments, the nanostructurecomposition can be deposited on one or more barrier layers.

In some embodiments, the nanostructure layer is cured after deposition.Suitable curing methods include photo-curing, such as UV curing, andthermal curing. Traditional laminate film processing methods,tape-coating methods, and/or roll-to-roll fabrication methods can beemployed in forming a nanostructure layer.

In some embodiments, the nanostructure compositions are thermally curedto form the nanostructure layer. In some embodiments, the compositionsare cured using UV light. In some embodiments, the nanostructurecomposition is coated directly onto a barrier layer of a nanostructurefilm, and an additional barrier layer is subsequently deposited upon thenanostructure layer to create the nanostructure film. A supportsubstrate can be employed beneath the barrier film for added strength,stability, and coating uniformity, and to prevent materialinconsistency, air bubble formation, and wrinkling or folding of thebarrier layer material or other materials. Additionally, one or morebarrier layers are preferably deposited over a nanostructure layer toseal the material between the top and bottom barrier layers. Suitably,the barrier layers can be deposited as a laminate film and optionallysealed or further processed, followed by incorporation of thenanostructure film into the particular lighting device. Thenanostructure composition deposition process can include additional orvaried components, as will be understood by persons of ordinary skill inthe art. Such embodiments will allow for in-line process adjustments ofthe nanostructure emission characteristics, such as brightness and color(e.g., to adjust the quantum dot film white point), as well as thenanostructure film thickness and other characteristics. Additionally,these embodiments will allow for periodic testing of the nanostructurefilm characteristics during production, as well as any necessarytoggling to achieve precise nanostructure film characteristics. Suchtesting and adjustments can also be accomplished without changing themechanical configuration of the processing line, as a computer programcan be employed to electronically change the respective amounts ofmixtures to be used in forming a nanostructure film.

Barrier Layers

In some embodiments, the molded article comprises one or more barrierlayers disposed on either one or both sides of the nanostructure layer.Suitable barrier layers protect the nanostructure layer and the moldedarticle from environmental conditions such as high temperatures, oxygen,and moisture. Suitable barrier materials include non-yellowing,transparent optical materials which are hydrophobic, chemically andmechanically compatible with the molded article, exhibit photo- andchemical-stability, and can withstand high temperatures. In someembodiments, the one or more barrier layers are index-matched to themolded article. In some embodiments, the matrix material of the moldedarticle and the one or more adjacent barrier layers are index-matched tohave similar refractive indices, such that most of the lighttransmitting through the barrier layer toward the molded article istransmitted from the barrier layer into the nanostructure layer. Thisindex-matching reduces optical losses at the interface between thebarrier and matrix materials.

The barrier layers are suitably solid materials, and can be a curedliquid, gel, or polymer. The barrier layers can comprise flexible ornon-flexible materials, depending on the particular application. Barrierlayers are preferably planar layers, and can include any suitable shapeand surface area configuration, depending on the particular lightingapplication. In some embodiments, the one or more barrier layers will becompatible with laminate film processing techniques, whereby thenanostructure layer is disposed on at least a first barrier layer, andat least a second barrier layer is disposed on the nanostructure layeron a side opposite the nanostructure layer to form the molded articleaccording to one embodiment. Suitable barrier materials include anysuitable barrier materials known in the art. In some embodiments,suitable barrier materials include glasses, polymers, and oxides.Suitable barrier layer materials include, but are not limited to,polymers such as polyethylene terephthalate (PET); oxides such assilicon oxide, titanium oxide, or aluminum oxide (e.g., SiO₂, Si₂O₃,TiO₂, or Al₂O₃); and suitable combinations thereof. Preferably, eachbarrier layer of the molded article comprises at least 2 layerscomprising different materials or compositions, such that themulti-layered barrier eliminates or reduces pinhole defect alignment inthe barrier layer, providing an effective barrier to oxygen and moisturepenetration into the nanostructure layer. The nanostructure layer caninclude any suitable material or combination of materials and anysuitable number of barrier layers on either or both sides of thenanostructure layer. The materials, thickness, and number of barrierlayers will depend on the particular application, and will suitably bechosen to maximize barrier protection and brightness of thenanostructure layer while minimizing thickness of the molded article. Inpreferred embodiments, each barrier layer comprises a laminate film,preferably a dual laminate film, wherein the thickness of each barrierlayer is sufficiently thick to eliminate wrinkling in roll-to-roll orlaminate manufacturing processes. The number or thickness of thebarriers may further depend on legal toxicity guidelines in embodimentswhere the nanostructures comprise heavy metals or other toxic materials,which guidelines may require more or thicker barrier layers. Additionalconsiderations for the barriers include cost, availability, andmechanical strength.

In some embodiments, the nanostructure film comprises two or morebarrier layers adjacent each side of the nanostructure layer, forexample, two or three layers on each side or two barrier layers on eachside of the nanostructure layer. In some embodiments, each barrier layercomprises a thin glass sheet, e.g., glass sheets having a thickness ofabout 100 μm, 100 μm or less, or 50 μm or less.

Each barrier layer of the molded article can have any suitablethickness, which will depend on the particular requirements andcharacteristics of the lighting device and application, as well as theindividual film components such as the barrier layers and thenanostructure layer, as will be understood by persons of ordinary skillin the art. In some embodiments, each barrier layer can have a thicknessof 50 μm or less, 40 μm or less, 30 μm or less, 25 μm or less, 20 μm orless, or 15 μm or less. In certain embodiments, the barrier layercomprises an oxide coating, which can comprise materials such as siliconoxide, titanium oxide, and aluminum oxide (e.g., Sift, Si₂O₃, TiO₂, orAl₂O₃). The oxide coating can have a thickness of about 10 μm or less, 5μm or less, 1 μm or less, or 100 nm or less. In certain embodiments, thebarrier comprises a thin oxide coating with a thickness of about 100 nmor less, 10 nm or less, 5 nm or less, or 3 nm or less. The top and/orbottom barrier can consist of the thin oxide coating, or may comprisethe thin oxide coating and one or more additional material layers.

Molded Articles with Improved Properties

In some embodiments, a molded article prepared using the nanostructurecompositions described herein shows an EQE of between about 1.5% andabout 20%, about 1.5% and about 15%, about 1.5% and about 12%, about1.5% and about 10%, about 1.5% and about 8%, about 1.5% and about 4%,about 1.5% and about 3%, about 3% and about 20%, about 3% and about 15%,about 3% and about 12%, about 3% and about 10%, about 3% and about 8%,about 8% and about 20%, about 8% and about 15%, about 8% and about 12%,about 8% and about 10%, about 10% and about 20%, about 10% and about15%, about 10% and about 12%, about 12% and about 20%, about 12% andabout 15%, or about 15% and about 20%. In some embodiments, thenanostructure composition comprises quantum dots. In some embodiments,the molded article is a light emitting diode.

The photoluminescence spectrum of the molded articles can coveressentially any desired portion of the spectrum. In some embodiments,the molded articles have a emission maximum between 300 nm and 750 nm,300 nm and 650 nm, 300 nm and 550 nm, 300 nm and 450 nm, 450 nm and 750nm, 450 nm and 650 nm, 450 nm and 550 nm, 450 nm and 750 nm, 450 nm and650 nm, 450 nm and 550 nm, 550 nm and 750 nm, 550 nm and 650 nm, or 650nm and 750 nm. In some embodiments, the molded articles have an emissionmaximum of between 450 nm and 550 nm. In some embodiments, the moldedarticles have an emission maximum of between 550 nm and 650 nm.

The size distribution of the molded articles prepared using thenanostructure compositions described herein can be relatively narrow. Insome embodiments, the molded articles prepared using the nanostructurecompositions described herein have a full width at half-maximum ofbetween about 10 nm and about 50 nm, about 10 nm and about 45 nm, about10 nm and about 35 nm, about 10 nm and about 30 nm, about 10 nm andabout 25 nm, about 10 nm and about 22 nm, about 10 nm and about 20 nm,about 10 nm and about 15 nm, about 15 nm and about 50 nm, about 15 nmand about 45 nm, about 15 nm and about 35 nm, about 15 nm and about 30nm, about 15 nm and about 25 nm, about 15 nm and about 22 nm, about 15nm and about 20 nm, about 20 nm and about 50 nm, about 20 nm and about45 nm, about 20 nm and about 35 nm, about 20 nm and about 30 nm, about20 nm and about 25 nm, about 20 nm and about 22 nm, about 22 nm andabout 50 nm, about 22 nm and about 45 nm, about 22 nm and about 35 nm,about 22 nm and about 30 nm, about 22 nm and about 25 nm, about 25 nmand about 50 nm, about 25 nm and about 45 nm, about 25 nm and about 35nm, about 25 nm and about 30 nm, about 30 nm and about 50 nm, about 30nm and about 45 nm, about 30 nm and about 35 nm, about 35 nm and about50 nm, about 35 nm and about 45 nm, or about 45 nm and about 50 nm. Insome embodiments, the molded articles prepared using the nanostructurecompositions described herein have a full width at half-maximum ofbetween about 15 nm and about 30 nm.

EXAMPLES

The following examples are illustrative and non-limiting, of theproducts and methods described herein. Suitable modifications andadaptations of the variety of conditions, formulations, and otherparameters normally encountered in the field and which are obvious tothose skilled in the art in view of this disclosure are within thespirit and scope of the invention.

Example 1

Quantum Dot Synthesis

Quantum dots were synthesized using procedures described in U.S. PatentAppl. Publication Nos. 2017/0066965 and 2017/0306227 and in U.S. patentapplication Ser. No. 16/422,242.

Example 2

Ligand Exchange

Carboxylate ligands were exchanged for halozincate ligands (e.g.,tetrachlorozincate, tetrafluorozincate, or dichlorodifluorozincate)which were expected to undergo electrochemical oxidation at a highervoltage than carboxylate ligands. In a subsequent step, potassiumcounterions of the tetrafluorozincate-capped nanostructures wereexchanged for tetraalkylammonium cations, which enabled solubility innon-polar solvents and made the exchanged nanostructures compatible withtypical fabrication processes for preparing electroluminescent quantumdot light emitting diodes. FIG. 1 is a flow chart showing ligandexchange of carboxylate-capped nanostructures withtetrafluorozincate-capped nanostructures with tetraalkylammonium anionsor didecyldimethylammonium anions.

The ligand exchange process is shown in FIG. 1 . In the first step,t-butylammonium fluoride (TBAF) and zinc difluoride (ZnF₂) were admixedin N-methylformamide (NMF) at room temperature to produce the dianionichalozincate TBA₂ZnF₄. In the second step, the dianionic halozincateTBA₂ZnF₄ and oleate-capped quantum dots (QD-OA) were admixed in amixture of toluene and NMF at 70° C. to produce TBA-ZnF₄-capped quantumdots. In the third step, the TBA-ZnF₄-capped quantum dots were washedwith toluene. In a fourth step, TBA-ZnF₄-capped quantum dots wereadmixed with didecyldimethylammonium chloride (DDA-Cl) to produceDDA-ZnF₄-capped quantum dots. In a fifth step, the DDA-ZnF₄-cappedquantum dots were precipitated with acetonitrile. In a sixth step, theDDA-ZnF₄-capped quantum dots were redispersed in toluene or octane inpreparation for use in a device.

Example 3

Nanostructure Ink Compositions

Nanostructure ink compositions were formulated using fully dispersed redInP/ZnSe/ZnS quantum dots with DDA-ZnF₄ ligands, JEFFAMINE M-1000 (as apoly(alkylene oxide) additive), and at least one solvent as shown inTABLE 3.

TABLE 3 Nanostructure Ink Compositions Quantum Dot M1000 Ink loadingloading Density Viscosity Sample Solvents (wt %) (wt %) (g/mL) (mPa*s)Jetting Test 1 1-methoxynaphthalene: 1.7 0.2 1.08 6.1 Goodn-octylbenzene (9:1) 2 1-methoxynaphthalene: 3.3 0.2 1.09 6.8 Not testedn-octylbenzene (9:1) 3 3-phenoxytoluene: 1.8 0.1 1.03 4.3 Poor (wetsn-octylbenzene (9:1) nozzle) 4 cyclohexylbenzene: 2.0 0.05 0.91 1.6 Poor(nozzle 4-methylanisole (1:1) plate cleaning hard) 51-methoxynaphthalene: 1.7 0.2 1.09 5.3 n-decylbenzene (9:1) 61-methoxynaphthalene: 1.7 0.2 1.08 4.9 cyclohexylbenzene (9:1)

As can be seen in TABLE 3, varying amounts of the poly(alkylene oxide)additive JEFFAMINE M-1000 can be used. In order to achieve the best inkcompositions, a minimum loading of poly(alkylene oxide) additive isrequired. The minimum amount depends on the choice of solvent and thequantum dot loading. For example, for a loading of 1.7 weight % ofquantum dots in a solvent mixture of 3-phenoxytoluene:octylbenzene(9:1), it was found that a JEFFAMINE M-1000 loading of 0.05 weight % wasnot sufficient to obtain a clear dispersion; however, using a loading of0.1 weight % of JEFFAMINE M-1000, full dispersion was observed (see InkSample 3). And, in the solvent mixture cyclohexylbenzene:4-methylanisole(1:1), a lower JEFFAMINE M-1000 loading of 0.05 weight % was sufficientto obtain full dispersion because the solvent mixture has a higherproportion of the more non-polar solvent cyclohexylbenzene (see InkSample 4). In general, a minimum poly(alkylene oxide) additive loadingof 2 weight % relative to the quantum dot loading is required for fulldispersion.

Since the additive will remain in the quantum dot film that isdeposited, it is also desirable not to use an excess that couldpotentially change the device properties. Hence, the poly(alkyleneoxide) additive loading should not exceed 40 weight % of the quantum dotloading. No detriment in device external quantum efficiency orphotoluminescence quantum yield was observed using a poly(alkyleneoxide) additive loading of 11 weight % relative to the quantum dotloading (see Ink Sample 1) compared to a control device with quantumdots spin-coated using octane with no poly(alkylene oxide) additive.

Example 4

Nanostructure Ink Composition 1

A stock solution of red InP/ZnSe/ZnS quantum dots with DDA-ZnF₄ ligandsin 2.3 mL of n-octane (density of quantum dots in stock solution=78mg/mL (180 mg of quantum dots)) was dried under vacuum in a Schlenkflask. The dried quantum dots were redispersed in n-octylbenzene (1 mL)containing JEFFAMINE M-1000 (0.02 mL). The mixture was stirred at 70° C.until a clear solution was obtained. The quantum dot solution was thendiluted with 1-methoxynaphthalene (9 mL) in which the quantum dotsremained well dispersed. The resulting ink was filtered through a PTFE0.22 μm filter and degassed under vacuum prior to transfer into an inkcartridge.

Example 5

Comparative Example for Nanostructure Ink Composition 1 (Example 4)

The nanostructure ink composition of Example 4 was prepared without apoly(alkylene oxide) additive.

A stock solution of red InP/ZnSe/ZnS quantum dots with DDA-ZnF₄ ligandsin 2.3 mL of n-octane (density of quantum dots in stock solution=78mg/mL (180 mg of quantum dots)) was dried under vacuum in a Schlenkflask. The dried quantum dots were redispersed in n-octylbenzene (1 mL).The mixture was stirred at 70° C. until a clear solution was obtained.The quantum dot solution was then diluted with 1-methoxynaphthalene (9mL) upon which the quantum dots agglomerated and the mixture turnedturbid. An ink formulation could not be obtained.

Example 6

Nanostructure Ink Composition 2

A stock solution of red InP/ZnSe/ZnS quantum dots with DDA-ZnF₄ ligandsin 13.9 mL of n-octane (density of quantum dots in stock solution=78mg/mL (1080 mg of quantum dots)) was dried under vacuum in a Schlenkflask. The dried quantum dots were redispersed in n-octylbenzene (3 mL)containing JEFFAMINE M-1000 (0.06 mL). The mixture was stirred at 70° C.until a clear solution was obtained. The quantum dot solution was thendiluted with 1-methoxynaphthalene (27 mL) in which the quantum dotsremained well dispersed. The resulting ink was filtered through a PTFE0.22 μm filter and degassed under vacuum prior to transfer into an inkcartridge.

Example 7

Nanostructure Ink Composition 3

A stock solution of red InP/ZnSe/ZnS quantum dots with DDA-ZnF₄ ligandsin 2.3 mL of n-octane (density of quantum dots in stock solution=78mg/mL (180 mg of quantum dots)) was dried under vacuum in a Schlenkflask. The dried quantum dots were redispersed in n-octylbenzene (1 mL)containing JEFFAMINE M-1000 (0.01 mL). The mixture was stirred at 70° C.until a clear solution was obtained. The quantum dot solution was thendiluted with 1-3-phenoxytoluene (9 mL) in which the quantum dotsremained well dispersed. The resulting ink was filtered through a PTFE0.22 μm filter and degassed under vacuum prior to transfer into an inkcartridge.

Example 8

Comparative Example for Nanostructure Ink Composition 3 (Example 7)

The nanostructure ink composition of Example 7 was prepared without apoly(alkylene oxide) additive.

A stock solution of red InP/ZnSe/ZnS quantum dots with DDA-ZnF₄ ligandsin 2.3 mL of n-octane (density of quantum dots in stock solution=78mg/mL (180 mg of quantum dots)) was dried under vacuum in a Schlenkflask. The dried quantum dots were redispersed in n-octylbenzene (1 mL)containing JEFFAMINE M-1000 (0.005 mL). The mixture was stirred at 70°C. until a clear solution was obtained. The quantum dot solution wasthen diluted with 3-phenoxytoluene (9 mL) in which the quantum dotsagglomerated and the mixture turned turbid. An ink formulation could notbe obtained.

Example 9

Nanostructure Ink Composition 4

A stock solution of red InP/ZnSe/ZnS quantum dots with DDA-ZnF₄ ligandsin 2.3 mL of n-octane (density of quantum dots in stock solution=78mg/mL (180 mg of quantum dots)) was dried under vacuum in a Schlenkflask. The dried quantum dots were redispersed in cyclohexylbenzene (5mL) containing JEFFAMINE M-1000 (0.005 mL). The mixture was stirred at70° C. until a clear solution was obtained. The quantum dot solution wasthen diluted with 4-methylanisole (5 mL) in which the quantum dotsremained well dispersed. The resulting ink was filtered through a PTFE0.22 μm filter and degassed under vacuum prior to transfer into an inkcartridge.

Example 10

Nanostructure Ink Composition 5

A stock solution of red InP/ZnSe/ZnS quantum dots with DDA-ZnF₄ ligandsin 13.9 mL of n-octane (density of quantum dots in stock solution=78mg/mL (1080 mg of quantum dots)) was dried under vacuum in a Schlenkflask. The dried quantum dots were redispersed in n-decylbenzene (0.2mL) containing JEFFAMINE M-1000 (0.004 mL). The mixture was stirred at70° C. until a clear solution was obtained. The quantum dot solution wasthen diluted with 1-methoxynaphthalene (1.8 mL) in which the quantumdots remained well dispersed. The resulting ink was filtered through aPTFE 0.22 μm filter and degassed under vacuum prior to transfer into anink cartridge.

Example 11

Nanostructure Ink Composition 6

A stock solution of red InP/ZnSe/ZnS quantum dots with DDA-ZnF₄ ligandsin 0.46 mL of n-octane (density of quantum dots in stock solution=78mg/mL (36 mg of quantum dots)) was dried under vacuum in a Schlenkflask. The dried quantum dots were redispersed in cyclohexylbenzene (0.2mL) containing JEFFAMINE M-1000 (0.004 mL). The mixture was stirred at70° C. until a clear solution was obtained. The quantum dot solution wasthen diluted with 1-methoxynaphthalene (1.8 mL) in which the quantumdots remained well dispersed. The resulting ink was filtered through aPTFE 0.22 μm filter and degassed under vacuum prior to transfer into anink cartridge.

Example 12

Nanostructure Ink Composition with Blue Quantum Dots

A stock solution of blue ZnSe/ZnS quantum dots with DDA-ZnF₄ ligands in1 mL of toluene (density of quantum dots in stock solution=18 mg/mL (18mg of quantum dots)) was dried under vacuum in a Schlenk flask. Thedried quantum dots were redispersed in 4-methylanisole (1 mL) containingJEFFAMINE M-1000 (0.005 mL). The mixture was stirred at 70° C. until aclear solution was obtained. The resulting ink was filtered through aPTFE 0.22 μm filter and degassed under vacuum prior to transfer into anink cartridge.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. It will be apparent to persons skilled in the relevant artthat various changes in form and detail can be made therein withoutdeparting from the spirit and scope of the invention. Thus, the breadthand scope should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the followingclaims and their equivalents.

All publications, patents and patent applications mentioned in thisspecification are indicative of the level of skill of those skilled inthe art to which this invention pertains, and are herein incorporated byreference to the same extent as if each individual publication, patentor patent application was specifically and individually indicated to beincorporated by reference.

What is claimed is:
 1. A nanostructure composition comprising: (a) atleast one organic solvent; (b) at least one nanostructure comprising acore and at least one shell, wherein the at least one shell comprises afirst shell comprising ZnSe and a second shell comprising ZnS, whereinthe nanostructure comprises inorganic ligands bound to the surface ofthe at least one nanostructure; and (c) at least one poly(alkyleneoxide) additive.
 2. The nanostructure composition of claim 1, whereinthe core comprises InP.
 3. The nanostructure composition of claim 1,wherein the inorganic ligands comprise a halometallate anion.
 4. Thenanostructure composition of claim 3, wherein the halometallate anion isfluorozincate, tetrafluoroborate, or hexafluorophosphate.
 5. Thenanostructure composition of claim 3, wherein the halometallate anionhas the structure of one of Formulas (I)-(III): MX₃ ⁻(I); MX_(4-x)Y_(x)⁻ (II); or MX_(4-x)Y_(x) ²⁻ (III); wherein: M is selected from the groupconsisting of Zn, Cd, Hg, Cu, Ag, and Au; X is selected from the groupconsisting of Br, Cl, F, and I; Y is selected from the group consistingof Br, Cl, F, and I; and x is 0, 1, or
 2. 6. The nanostructurecomposition of claim 3, wherein the halometallate anion is CdCl₃ ⁻,CdCl₄ ²⁻, CdI₃ ⁻, CdBr₃ ⁻, CdBr₄ ²⁻, InCl₄ ⁻, HgCl₃ ⁻, ZnCl₃ ⁻, ZnCl₄ ²⁻, or ZnBr₄ ²⁻.
 7. The nanostructure composition of claim 1, wherein theinorganic ligands comprise an organic cation selected from the groupconsisting of a tetraalkylammonium cation, an alkylphosphonium cation, aformamidinium cation, a guanidinium cation, an imidazolium cation, and apyridinium cation.
 8. The nanostructure composition of claim 1, whereinthe inorganic ligands comprise a tetraalkylammonium cation selected fromthe group consisting of dioctadecyldimethylammonium,dihexadecyldimethylammonium, ditetradecyldimethylammonium,didodecyldimethylammonium, didecyldimethylammonium,dioctyldimethylammonium, bis(ethylhexyl)dimethylammonium,octadecyltrimethylammonium, oleyltrimethylammonium,hexadecyltrimethylammonium, tetradecyltrimethylammonium,dodecyltrimethylammonium, decyltrimethylammonium,octyltrimethylammonium, phenylethyltrimethylammonium,benzyltrimethylammonium, phenyltrimethylammonium,benzylhexadecyldimethylammonium, benzyltetradecyldimethylammonium,benzyldodecyldimethylammonium, benzyldecyldimethylammonium,benzyloctyldimethylammonium, benzyltributylammonium,benzyltriethylammonium, tetrabutylammonium, tetrapropylammonium,diisopropyldimethylammonium, tetraethylammonium, andtetramethylammonium.
 9. The nanostructure composition of claim 1,wherein the inorganic ligands comprise a ZnF₄ ⁻anion and adidecyldimethylammonium cation.
 10. The nanostructure composition ofclaim 1, wherein the inorganic ligands comprise an alkylphosphoniumcation selected from the group consisting of tetraphenylphosphonium,dimethyldiphenylphosphonium, methyltriphenoxyphosphonium,hexadecyltributylphosphonium, octyltributylphosphonium,tetradecyltrihexylphosphonium, tetrakis(hydroxymethyl)phosphonium,tetraoctylphosphonium, tetrabutylphosphonium, andtetramethylphosphonium.
 11. The nanostructure composition of claim 1,wherein the at least one organic solvent is selected from the groupconsisting of 1-tetralone, 3-phenoxytoluene, acetophenone,1-methoxynaphthalene, n-octylbenzene, n-nonylbenzene, 4-methylanisole,n-decylbenzene, p-diisopropylbenzene, pentylbenzene, tetralin,cyclohexylbenzene, chloronaphthalene, 1,4-dimethylnaphthalene, 3-isopropylbiphenyl, p-methylcumene, dipentylbenzene, o-diethylbenzene,m-diethylbenzene, p-diethylbenzene, 1,2,3,4-tetramethylbenzene,1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene, butylbenzene,dodecylbenzene, 1-methylnaphthalene, 1,2,4-trichlorobenzene, diphenylether, diphenylmethane, 4-i sopropylbiphenyl, benzyl benzoate,1,2-bi(3,4-dimethylphenyl)ethane, 2-isopropylnaphthalene, dibenzylether, and combinations thereof.
 12. The nanostructure composition ofclaim 1, wherein the at least one poly(alkylene oxide) has Formula (IV):

wherein: x is 1 to 100; y is 0 to 100; R^(1A) and R^(1B) independentlyare H or C₁₋₂₀ alkyl; R² is C₁₋₂₀ alkyl; X₁ is a bond or C₁₋₁₂ alkyl; X₂is a bond, —O—, —OC(═O)—, or amido; FG is —OH, —NH₂, —NH₄ ⁺, —N₃,—C(═O)OR³, —P(═O)(OR⁴)₃, or —P(R⁵)₄; R³ is H, C₁₋₂₀ alkyl, or C₆₋₁₄aryl; R⁴ is independently H, C₁₋₂₀ alkyl, or C₆₋₁₄ aryl; and R⁵ isindependently H, C₁₋₂₀ alkyl, or C₆₋₁₄ aryl.
 13. The nanostructurecomposition of claim 12, wherein x is ₂₋₂₀ and y is ₁₋₁₀.
 14. Thenanostructure composition of claim 12, wherein R^(1A) is H and R^(1B) isCH₃.
 15. The nanostructure composition of claim 12, wherein the at leastone poly(alkylene oxide) has Formula VI:

wherein: x is 1 to 100; y is 0 to 100; and R² is C₁₋₂₀ alkyl.
 16. Thenanostructure composition of claim 15, wherein x is 19, y is 3, and R₂is —CH₃.
 17. A process comprising depositing the nanostructurecomposition of claim 1 on a substrate to form a layer comprising thenanostructure composition.
 18. The process of claim 17, wherein thedepositing is by inkjet printing.
 19. The process of claim 17, furthercomprising depositing a first transport layer on a first conductivelayer, the first transport layer being configured to facilitatetransport of holes from the first conductive layer to the layercomprising the nanostructure composition; and depositing a secondtransport layer on the layer comprising the nanostructure composition,the second transport layer configured to facilitate transport ofelectrons from a second conductive layer to the layer comprising thenanostructure composition.
 20. The process of claim 17, wherein thenanostructure composition is deposited in a pattern.
 21. A lightemitting diode comprising: (a) a first conductive layer; (b) a secondconductive layer; and (c) an emitting layer between the first conductivelayer and the second conductive layer, wherein the emitting layercomprises at least one population of nanostructures, wherein thenanostructures comprise (i) at least one organic solvent; (ii) at leastone nanostructure comprising a core and at least one shell, wherein theat least one nanostructure comprises inorganic ligands bound to thesurface of the at least one nanostructure; and (iii) at least onepoly(alkylene oxide) additive.